LO refusing fm

hi mummies! ftm mom here, my LO is fully fed with fm & he has suddenly been refusing fm since about a month ago. he's 5 months right now. when i would give him fm, he would make a puking face or just straight up refusing, crying until i stop giving him.. he only accepts it when he's truly hungry. supposedly, he should be drinking 150ml right now.. however he cant even finish 120ml most of the time. should i change the fm, bottle, teat or which way should i explore in order to provide him comfort when drinking fm? i had tried changing the teat as sometimes he choke on the milk when feeding.. now he's still using 0-3 months teat and seems more comfortable than he was when using 3-6 months teat as he would get angry everytime he chokes on the milk. he would choke on it even when lying in a half upright position #adviceplease #FTM #FormulaFedBabies