Preemie question

Ok so my little boy was born 2 months early, we're coming up on his due date tho this Friday :) and he is doing great! I am strictly breast feeding (including bottle feeds). He spent a month in the nicu and the hardest thing for him was bottle feeding, he would always get too much and drop his heart rate and then lots of times just stop breathing (preemies often forget). He is doing much better now tho and eating great, but I'm still using bottles from the nicu. Which were real slow release. Has anyone on here had to switch and been as nervous as I am about him choking... or know which bottles would be best to get?? I'm just a little nervous to switch but need to cuz these bottles are now almost too small.