well it's a good thing that she's in a loving and caring home who are doing their best to make her comfortable and have brought her back from being a bag full of bones.
And since you got her around when you think she was bred, I would think the foal would be healthy since it started getting all the proper nutrition. (I'm just taking a guess here. I really don't know)
I would see if a. Someone could take her in where there is proper shelter, or b. Since you have a bit of time, see if you could make a quick shelter for her.