Equestrians help

Ok so my horse has a problem with caring her head high rushing and when she canters doing flat she will only for a few strides before stopping I use alot of leg and sometimes have a crop not all the time tho and other stuff right now I'm working on them as well as a few other things and my own riding i ride by myself in the paddock/ arena we use a paddock as a jumping and another one as a flat work and we have a spare one if they are being used by horses or cattle in them at the time I. Trail ride and do cattle work I'm only just getting into English and flat work my uncle helps me out once a week if he can otherwise I'm by myself I do get lessons sometimes from my cousin but we both have very busy schedules so it's hard to get lessons does anyone have any excersizes or tips for becoming better I would like to compete one day she's always been used for cattle work trail riding she had the same problem with her old owner we have both gotten alot better