M.S.
Both of my little ones had reflux really bad so I feel for you and how hard you life is! I used a whole group of things to make it better, and I hope some of this helps you.
1. I used the playtex dropins with latex slow flow nipples, they still use the same one now that they are older.
2. Give Mylanta as needed for gas and acid burn. This works great instantaneously.
3. Use Zantac and if its not enough then switch to Prevacid, but talk to doctor first.
4. Sleep in infant car seat or simliar angle because it helps keep the acid down instead of in the throat. We actually used the Graco Sweetpeace Soother because it moved as well and that helped a lot!
5. Feed smaller amounts more often. I think at 3 months we were about 2 to 2.5 oz every 1.5 hours instead of every 3.
6. If you are dealing with colic then look into a milk Protein allergy, its not lactose its the protein so you should use soy or Alimentum type formula. Soy tends to cause constipation, so you may need to mix or do all alimentum.
7. Hyland's Colic pills...These are a life saver and all parents should be given them in my opinion!
I hope this helps, but to answer your original question, I would keep with the slow nipple because when you give more faster the stomach can get overwhelmed and then vomiting can occur. I didn't use the Dr. Browns because of all the little pieces. I also saw that they don't ever stop dripping so the baby can't stop to take a breath. Is that a problem for her? Good luck mama! this can be so hard but it usually goes away by 9-12 months.