I agree with DJD. Do more flatwork. Work on rythm, tempo, and even-ness of all the gaits. I think that you should get a flatwork and jumping trainer. You two arn't doing anything wrong at all, your having fun and that's good. That's how my best friend started her gaited 14.1 hand Paso Gelding. She just started expirementing with low jumps and when she decided she wanted to get serious so she started working more on flatwork and control. She used to be able to only ride him in a harsh shank bit and jump no more than one foot. Now she can ride him bridleless(though she normally rides in a bridle, she uses a D ring bit) and jump him over a three foot course in a halter... bareback :) She's never had a trainer. But it took her three years and it would've taken so much less time and made the expirence much less frustrating if she had, he's retired now though.
Do you want to show him? He seems like he'd make a nice gaited hunter, you don't see too many gaited horses with that headset! I think to help with your postition, go around on the flat in two point and work on stretching into your heels. When you jump raise your stirrups. Release more, just work on gently sliding your hands up the neck before you get to big releases. When you jump think "my back needs to be straight, I need to stay in two point" that really helped me when I first started jumping :) Good luck with him
"Riding is not Equitation... The moment you believe it is, is the moment you quit riding."