6 weeks old constantly spitting up

My son just turned 6 weeks old today and has been spitting up more than normal for weeks. He is breast fed, I'm exclusive pumping and feeding my bottle. We burp him frequently and give gas drops with each feed. Initially he had lost weight at his 1 month appointment, bit has since started gaining again after we started to thicken the breast milk with Enfamil AR, changed nipple sizes and started him on Prevavid. The pediatrician isn't concern since he shower great weight gain and still has plenty of wet and dirty diapers. I'm just still concerned because it seems like a lot for him. Some feeds he does fine and only has wet burps, others he will spit up 4 or 5 times afterwards, sometimes an hour or two after he's done eating. He always spits up at night in his bassinet, so he's always wet when we get him up. The only thing I haven't done is cut out dairy, I don't feel strongly that he has a milk protein allergy, his poops are not mucousy and the pediatrician didn't mention it, but at this point I don't know what else it could be. Does anyone have any similar experience? The doctor thinks he is just a "leaky" baby and will spit up more than usual and will eventually outgrow it, I just hate it for him and am looking for any other answers.