What am I doing wrong ?

My son is 8 weeks and recently I've noticed when its time to eat he spits a lot of his milk, I don't think it's reflux because it's during the feeding. It's as if he's rushing to drink his bottles and everything just flies out, when he turned a month I went from 0+ size nipple for his bottles to 1+ and now that I noticed that I thought it could be because the extra hole on the nipple so I went back down to 0+ slow flow and he still does the exact same thing . Then I thought i was feeding him too often (4 oz every 4 hrs) and he didn't want his bottle that's why he'd spit it so I let him sleep till he cried for his bottle and that also didn't work. I can't think of what else to change or what to do , could anyone help? Or what may be wrong ?

(He's on similac sensitive)