As long as she's inside cut the oil to half, the alfalfa also. The belly is mainly caused by not moving and eating so-so hay. Good hay doesn't give this kind of belly. BUT....good news is, it'll go away once she has better forage and moves.
I don't find her to fat either. Just the belly. You could switch to alfalfa/ timothy or alfalfa/ orchard pellets and give her more of these, to fill her up with low bulk fiber, and hope she eats less of the bulky hay. If you do that, an once of oil a meal will be fine.