C.A.
I went through a similar thing-my daughter had reflux.
We started out with the Playtex drop ins and they were great for two months. But by month 3 the reflux was in fill swing and one of the things we had to do to help her with that was try different bottles.
I figured out after buying two large sets of expensive bottles to just buy two and see how it goes for a couple of days-if we made it past three days then I went ahead and bought the big set of them.
We wound up going with the Avent bottles.