I’m a Ftm and I’m looking for advice .

My son is 6 weeks old , and is bottle fed with formula and occasional breast milk ( I don’t produce a lot , so I pump)

We have tried numerous bottles - but came to an agreement that tommy tippy is the way to go. We started using size 0 .. it was going good for a while but he started to drink an ounce , then suck really hard , breath really hard then arch his back and get pissed and spit all that milk out . So we thought , maybe he’s getting frustrated cause we’re sitting him wrong , or maybe he’s not burped enough , or maybe he’s getting frustrated that the nipple is so slow ?

All of which we tried to resolve - we sat him correctly , made sure he was burped when he would cry , and even changed the nipple to a 1 !

He still does it and I’m so frustrated . Not sure what to do !!! help ??