Balance issues- me not the horse

I need some advice to build my core strength and balance. I kept thinking my horses weren't picking up their feet, or it was this training issue vs. another but I'm convinced, a major problem is my balance- that's why they trip or stumble.

I ride both english and western, though feel a little safer english- not sure why, but it has something to do with the stirrups. I have ridden bareback a few times, tried my feet out of the stirrups (holy crap, I was scared).

I want to be able to trot the entire length of my pasture, but i'm terrified because my horses stumble and I feel like I'll come off over their heads. This also applies to when my horses pull their heads down and I should bump them forward onto the bit, but I'm scared of: 1) they'll stumble and i'll fall 2) they'll break into a canter (i stick to walk/trot 90% of the time)

To make matters worse, I can only ride once or twice a week due to work and home obligations. As bad as this sounds, I am a full grown adult who has been riding most of my life. I've had some bad experiences as of late and now I am as timid as they come when it comes to riding.

Suggestions? I havea trainer who is great but we are still trying to work out scheduling conflicts.

If you have a friend you trust I would do some riding on a lunge line. Let your friend lunge you around and you just work on balance and seat. Put your arms out to the side, out in front, one in front one behind and. Just really get comfortable being on a horse without the worry of having to steer. Start at a walk and then graduate to a trot and canter when you are comfortable.

I totally agree with the lunge line idea. You need to build your confidence!
Balance has a lot to do with body position, leg position, core strength, and leg strength. Two of the biggest things that will cause you to lose your balance and tip forward are looking down at your horse and letting your legs slip too far back. You'll find that those two parts of your body have a huge effect on your overall position and security; when your head is down and your legs are back, your whole body pitches forward. When your body is forward, one little stumble can offset your balance even more and possibly land you on the ground.
So. Focus on looking up and ahead to where you're going. If you're on a circle such as on a lunge line, keep your body moving in the direction of the circle but don't let yourself lean and look in to the circle. Ride with your chin up as if you have confidence, and you'll end up with real confidence! As for your leg, keep your calf slightly behind the girth at all times and think of hugging your horse with your legs. You shouldn't be gripping with your knees, but there should be no gap between your legs and the horse. Keep your heels down to help anchor you and think of lining your body up ear/shoulder/hip/ankle. Above all, have confidence! You've been riding for a long time and you know what to do, your fear is just getting in the way of memory and performance.
To build your leg and core strength, gradually work in 5-10 minutes of stirrup-free riding every time you ride. I know it's scary at first, but you have to trust yourself! Start out just on the longe line walking and keeping your legs in the same line up as you would with stirrups, but slightly longer. Don't just let your legs dangle or you'll end up slipping and feeling insecure when you trot and canter or when your horse spooks. Gradually work up to sitting and posting trot without stirrups (excellent for the core, inner legs, balance, and stamina!). You'll be pretty sore after your first few rides, but it'll be worth it in the end! Who knows - with all the confidence you'll gain, you could be galloping around the pastures in no time

It could be both of you. Since MeLikesUke gave you excellent advice on you, does your horse does this with others?

I've only let anyone ride my paint, and yes, I heard comments of him mis-stepping or tripping. She wasn't exactly experienced though. I havent let anyone ride my Connemara/QH but he definitely has better balance. My position is decent (per my instructor) and for some reason, I FEEL better when she is there. The part about my paint dropping his head is a big issue. He is almost on the ground pulling the reins, which pulls me forward too.
I know it doesn't sound like it, but I am always aware of keeping my head and eyes forward and steering is never a problem. I have quiet hands except when im being yanked on. I like to do little half halts and bump with my leg. I definitely have no confidence but I also don't have anyone around that I'd trust to lunge me, besides my instructor.
I will take your advice and ensure to fit time in EVERY ride without stirrups, and maybe even hop on bareback a few times a week- I can squeeze that in.
I will be more aware of my feet, in case I'm slipping them back. Thank you everyone.

Hmm, has your instructor ever ridden him? It sounds like he's taking advantage over you having no confidence and is being a punk. Maybe it'd be a good idea to have her hop on your horse and see if she can get him to cut the antics.

What helped me was my trainer not letting me ride with stirrups... also do you look down alot? If I look down it throws my balance off, I think this applies for everybody.

I think tripping a lot has got to be the horse's problem. You ight be making it harder for the horse, by leaning forward too much, and if you are gripping wiht you knee, then when the hrose trips it can make you feel like you'll be catapulted over his head.
The way to feel better about that is to sit up straighter, realy drop your heel down and feel your calf against the horse's side.

Is the pasture the only place you have to ride? I think you need to get the hrose moving faster to lessen the incidence of tripping. Making him step up more vigorously will make him lift up his feet more. But, it means the horse goes faster and that can be scary. I sometimes reach around behind myself and grab the cantle of my english saddle when I want to remind myself not to lean forward, and I ride one handed for a bit, holding onto the cantle. It feels nice.

Would you be comfortable taping your horse worked freely and then with you on him?

My horse used to trip a lot and it came down to two things. His inexperience (so we slowly started adding more poles to trot over) and his feet were in need of adjusting as they weren't trimmed properly.

Tiny, I agree. They both need to be worked faster to correct some of the problems I'm having. I have my front yard which is in decent shape but does have 2 holes that I need to mark to avoid them. I know people trot and canter on trails, so obviously a horse can do this without falling and making me fall, I just havent figured out how, since mine could trip in perfect footing.

I sit very straight ,always roll my shoulders back. I do see that in some pics im sitting in a chair postiion. I'm going to post some pics from sundays ride (yes im in the round pen, lol!!) I did eventually take him out but just at a walk.