Overfeeding?

My LO is 1 months 8 days. Currently I am feeding him with mixed of bm and formula. For formula is 100ml and bm is 110ml. However most of time he is not burping and puke out. Total one day intake is around 850ml or more. I am not sure am I overfeeding him that he can't burp and puke out. In the night, he can stretch until 4 hours until the next feeding Should I feed him lesser like 90ml?