Baby Reflux???!!! ?

Does anyone else have issues with their baby spitting up.... A LOT!!!! ??? My baby hasn't gained weight like I feel he should have by now. I've talked to his doctor, they've ran tests on him & said everything looks fine although he is under the weight percentile a tad bit. I've tried adding cereal to his milk, switching to milk allergy formula & none of Tht helped. He's now on the enfamil AR which kinda helps but still not seeing a huge weight gain. He is on medicine for the reflux but I heard all its good for is not messing up his esophagus with the acid tht comes up. He seems happy for the most part & he is very playful & active. He can roll both ways, sit himself up when laying in his boppy, Rock in a crawling position, hold his bottle, reach & grab things, etc. he smiles & talks to me so I'm not worried abt his milestones, just his weight gain. I don't want him to be underweight. His goes thru so many bibs & clothes. Sometimes I'm afraid to play with him bc I dont want to cause to him to spit up. He'll do it after hours of eating. Anyone else gone thru this? What helped you? I feel like I does so much better solids but I only give him cereal right now. I will be starting him on a full schedule of solids at 6months...