Any mamas using Enfamil AR?

SL

My little guy just switched to this last night as it was suggested to me by his pediatrician as he was spitting up a lot. I noticed it does seem to be thicker than the Enfamil Neuropro I had him on before. He drank a bottle fine last night using a size 1 nipple but struggled this morning, so I changed it to size 2 and now I’m just concerned that he may drink it too quickly. Any other mamas have experience with this?