Good for you, considering everyone's criticism with a level head, PrincessBarbie.
Since you have a Tractor Supply, what about buying some Standlee Alfalfa Pellets or Timothy/grass pellets? They are hay, just processed into pellets that are sometimes more palatable to horses, and I've found them to be very good quality. Pour water into the bucket of pellets 30 minutes or so before feeding it to her so that it is mushy. Start slow, but bring her up to eating 6-7 lbs per day. If you are feeding her alfalfa hay, give her grass hay pellets. If you feed her grass hay, give her alfalfa pellets.
You might look into finding a local hay supplier also, instead of TSC for your hay. I've found that while they are very reasonable about most things, their hay can be pricey because they only sell Tidy Wrap bales (at least where I live, anyways.) If you can find a supplier, you can get quite a few square bales at a time. Offer your filly 10-15 lb of hay (half a bale) daily if you are feeding pellets too, or anywhere from 20-25 lbs without pellets, as well as her rice bran. When looking for good hay, check to see if the hay smells good, is soft in texture (no huge stalks/brittle pieces), and still leafy. Hay that has all of those qualities is generally at least decent.
Having constant hay around will help her out a LOT and she'll probably be looking great in a few months!