Well I usually feed after I ride..and I feed two quarts of crimped oats. And the reason I grt frustrated is because I can get hurt if she decidss to run under our carport. On the ground etc I have the patience
Do you feed directly after riding? That could stem some of your problems too. She's anticipating getting fed when you're done riding. Sadie may be thinking "Oh, once she gets off my back, I get all this tack off me, I don't have to work, and I get a belly full of good chow!"
So she's going to be rotten the entire time hoping to win and get you off her back. My mare, Dandy, was VERY barn sour when I got her. She'd walk off really slow then as soon as you turned for home, you BETTER have a good hold on those reins because otherwise she'd shoot off like a rocketship. Luckily she wasn't mean enough to buck or anything. Just get REAL dancy, trot in place, and have fun with trying to stop her and make her stand still. She'd paw the ground and prance in place. I figured out it was because when we got home from a ride: BAM!! -Tack was off and as long as she was cooled down, she had a bucket of yummy bran and grain waiting for her. Of course she wanted to be done with the ride! To break her of this, when I got home from a ride I would walk her around the yard for a bit. Then when I got off, all I would do was marginally loosen her cinch (to be just a little more comfortable), tie her up, and wait 10-20 minutes before untacking her. Then, after pulling everything off and brushing her. Wait just a minute or two more before turning her loose with her grain. That way, it was INSTANT gratification when you got back home.
It sounds more like you're riding in just an area on your property? So you'd have to go about things a little differently. Same principle though. Do you have a fence? Does she act gate sour at all? Like her behavior gets worse while passing the gate or exit away from where you are riding?
How does she respect you on the ground? Sounds like she's just bullying you around a bit because she knows that you're still a little green yourself. :) I just caught up on some later posts here though and it sounds like you guys are starting to work things out a bit.
Only thing I can say is make sure your hands are real quiet (not pulling on her mouth) when she's being good. She's probably just being a brat when she starts trotting with her head low like that, but also you could be bumping her mouth (not even realizing it) when your trotting if your not real balanced yet and that's causing her to go down and try and escape from the pressure. I know my friends horses, that are extremely well schooled, would do that if I wasn't paying attention and got too "loud" with my hands. They'd pull their heads down or become a little unresponsive when I'd ask them things with my reins -it's because my hands got too busy and they're just bracing against it because they don't trust my hand. It has taken awhile, but I have been working on "quieting" my hands a lot and I have found that the horses are now more trusting and responsive to my hands. -Not saying this is your problem, just another possibility that could be adding to things and something good to think about.
Best of luck and keep us updated!