Per the instructions of our pediatrician, we add rice/oatmeal cereal to our 11 week olds bottle (reflux that has been significantly helped by adding 1 tablespoon of cereal to 4oz of formula). My problem is, I never seem to get the nipple opened up just right (without any adjustment/opening, it won't flow. I have tried using a needle to open the nipple a bit more but the flow is then too much). Any recommendations on how to get a nice (not too quick, not too slow) flow? We use the Dr. Brown's bottles....
Re: Thickening formula...how to adjust nipple
When we did this for DD1's reflux, we switched to the fast flow nipples. She was a bit older than your LO though when our pedi advised us to do this. You can always try a faster flow nipple (the opening is bigger) and see how your LO does with it.
Don't cut it yourself, you can make the flow too fast.
Get the Y cut nipples for your bottles.