How far up in Kentucky are you?
I know of a guy on the SE side of MTSU that raises fantastic hay and his prices were reasonable the last time I was up there. He raises mixed grass hay, bermuda hay and might even raise alfalfa.
I can PM you his name and phone if you think he's in reasonable driving distance.
Your other hay option might be to buy bagged hay at Tractor Supply, if you have a TSC close enough. They sell Standlee hay and hay cubes. I am really happy with Standlees hay cubes even if they are rock hard and I have to soak them. Standlee Hay Company - Home
As far as grain, I would get her off the sweet feed five minutes ago
It's sad that all you have for a major name feed is Purina. My county was like that until Tractor Supply came to town. We can get Nutrena at TSC now. I live in a Good Ole Boy County and Purina really ruled until a few years ago so I can understand and sympathize with your dilemma.
I don't use bagged feed (I mix my own) and I'm not really a Purina fan but if that's your only choice, that's your only choice. Even if the store does say they'll order something else in; that only works for a short time unless other people buy the product and also like it.
Stores have to buy a minimum amount and that amount can often be "by the pallet". You may find yourself buying a bag of feed six months down the road that actually came off the truck with the very first bag you bought
Their "Equine Junior" product might be worth looking into. It says from weanling to two years old but that doesn't mean the horse can't eat this product for another year os so. Purina Horse Feeds - EQUINE FAMILY
They also have Ultium Growth that looks pretty good. Purina Horse Feeds - ULTIUM
I don't like that Purina never lists all of the ingredients that go into the product.
You might consider adding some flax seed to her diet - it will help with hoof and coat health. Many folks just buy plain flax; I buy Omega-3 Horseshine. It can be bought at TSC but is really pricey. Three of my four horses get Omega-3 Horseshine and a bag lasts me about 5 weeks. They all have solid hooves with a nice natural shine to them.
You could start her out with just 1/8th measuring cup twice daily and see how she does. Omega Fields - Flaxseed and Omega-3 supplements
I hope this helps and because I have three TWH's and am Walking Horse nosey ---- who's on her papers? - lollol