Most doctors would say that if they are gaining weight well and they aren't too fussed, then to let it be and see how they do. I err on the other side, I would get it checked out. There are pediatric gastro intestinal specialists that do reflux and other stuff. Not digesting food or drink for 4 hours at a time, is consistent with both reflux, and also something called delayed gastric emptying, there are medicines that can be given to speed up the digestion of the milk so that it goes through faster.

If you don't want to go that far yet, I would take her to the health nurse and get her weighed regularly there, so that you have a basis using the same scales, and same circumstances, if she is vomiting that much, then she may start to loose weight soon if it isn't getting better.

Have you tried thickening the bottle to help it settle? It sometimes helps.