IMO it sounds like you and your horse really aren't a match. Horseback riding should be fun and generally not anxiety provoking. If your constantly worried about your horse acting up or possibly throwing you off your not having fun. Like wise your horse probably isn't either, not to mention the bad habits that are just becoming ingrained in her. A horse for a beginner with confidence issues should never buck/rear/bolt/kick, shouldn't be buddy sour and should be forgiving, steady, reliable, and predictable.
If I were you I would take lessons on a steady Eddie who is going to boost your confidence. I would make the decision to keep or sell your horse in the mean time. If your going to keep the horse I would have a trainer ride your horse. When you feel confident on the schoolie try the skills out on your mare.