Hello everyone) How do you feed a 3-month-old baby on a mixed diet? Ho…

Hello everyone) How do you feed a 3-month-old baby on a mixed diet? How much do you give in ml? I give 120ml during the day and 90 at night. But we're spitting up a lot, the pediatrician says this is normal. We went to a gastroenterologist, had an ultrasound, everything was normal they said. I thought it might be because of the bottle? Or am I giving too much? We have Avent bottle.