Silent reflux

My 7 week old was just diagnosed with silent reflux. He hasn't gained much since birth, he was born 8.3 and now at 7 weeks he weighs 8.15 which puts him in the 3rd percentile for weight. I'm breastfeeding every 2-3 hrs and I give him two pumped 5 oz bottles a day in morning and night. Dr just prescribed Prilosec and hopefully that will help otherwise I have to cut dairy. Any reflux Moms out there who can offer some advice or comfort? Dr said if it comes down to it and those things don't work we may have to switch to formula which I do not want to do at all. Thanks in advance.