Spit up/weight gain- 5 weeks old

Hello,

My daughter is 5 weeks and had her 1 month checkup yesterday. My concern was that she’s spitting up constantly (I called them 2 weeks ago and was told if she’s peeing and pooping good it wasn’t a worry- baby is happy). The pediatrician feels she has slow weight gain now due to reflux and has her on Pepcid. Pepcid does not seem to help. She started at 7 lb 8 oz then dropped after birth to 6 lb 11 oz. Yesterday she weighed 7 lb 15 oz.

Is that slow weight gain? Any other parents experience constant spit up but with a happy baby? She is bottle fed breast milk (I exclusively pump). She eats every 2 hours aroubd 2-3.5 hours per feed