So sick of the spit up!!!

So my LO is 19 weeks 4 days and she weighs about 11 lbs 13 oz. She has been on the smaller side this entire time. But at every doctors visit she is still gaining on her growth curve so the doctor isn’t concerned, says “she’s long and petite”. But it stresses me out bc she spits up sooo soooo much. Ahhhh!! Seriously I change my clothes at least 2-3 times a day and can change hers up to 6 times. I’ve tried to feed her less amounts but more frequently. I’ve tried 5 diff bottles. Doctor said try cereal in her bottle, has no effect. I’ve cut things out in my diet and tried diff formulas per doctor’s recommendation, (I breastfeed/pump then supplement 2 bottles at night). So now since her 4 month appt her doctor said we can try baby foods and cereal. She does great with that, barely spits it up. But it’s like anything out of a bottle just comes right back up. I give her around 4-4.5 oz during the day and her bottles at night are 5 oz. So she averages 24/25 oz a day I’d say. I’ve told the doctor that I’m concerned about her weight compared to her peers and I feel like she doesn’t gain as much or as fast bc of all the spit up. But again, he’s not worried and he said after 6 months the spit up should slow down a lot. I just feel like it’s never ending. Anyone else struggling with similar issues? Would you change your doctor?