Trot is good but jumping and cantering is a nightmare!?

So I have just restarted from the beginning and trying to retrain my horse another way. In another way I mean more forgiving and less pressure on the bit. For about a week or 2 we have just done walking and trotting. It's been going very well so this last week I have tried to canter again. She always has issues with falling through her left shoulder. Whenever you get her moving straight and ask her for a faster gait she has to fall through it before she picks it up. Also when you add leg at a faster gait she pins her ears back and swishes her tail around. So when I'm cantering she throws her head up in the air, picks up the pace, starts swishing her tail, pulls/holds the bit, and just seems very unhappy. Cantering to the right is also the worst! She kind off does this weird thing where she like, I don't know how to explain it, but she lifts her upper body up in the air a little bit and kind of launches forward. It's weird and frustrating. She also pulls on the bit so hard. But if I release the pressure on the bit at all she just goes faster and faster. Yes, we have had her teeth done and the vet said she needed hock injections and those were done about a month ago along with her back getting adjusted. Jumping is the same except worse-Faster and angrier. I don't know if this is of any importance but we cantered going up this hill at my barn and she was great. No pined ears or swishing tail.