She's a cutie. I would try to get her some more exercise to build her hindquarters and slim her down through the barrel. Lots of backing and uneven terrain. I don't know what you are feeding her or how serious you are about succeeding at halter, but a good quality hay makes a huge difference as well. Our horses were raised on poor quality grass hay (whatever my Dad harvested out of the pasture), but since we've moved and alfalfa is "affordable" here, they get alfalfa. Huge difference. Gives them a more sucked up athletic appearance. You could also try sweating her neck and getting a better fitting halter to show her in. Not a must but will hide flaws - and doesn't have to be super fancy. Good Luck!