in need of mommy help! PLEASE

I need the help of other mommies. Little miss will be 5 months old on the 19th (already I know!). She is still puking after every single feeding and will continue to do so on and off until the next bottle and the next, it is never ending. She has done this since she was born, she did it while on breast milk and still does it with her formula, I have even tried another brand..still the same. I know a lot of other mommies that have babies Tegan's age and non of them are still pukey. I have expressed my concerns to the dr when Tegan was little and I was told that she probably has reflux like most babies have. Tegan is gaining weight right on track and thriving so nothing more was ever said. I was told to thicken her formula and keep her elevated. None of that helped. She can be sitting perfectly upright and still throw up, thickening her formula hasn't helped either. The only time she doesn't puke is if she eats her baby cereal. Do you think maybe Tegan is a bit sensitive to lactose??? Should I try giving her lactose free formula? Would it hurt to give her lactose free formula? I know she is healthy and growing big but the puking is getting old. she goes through many outfits and bibs a day, and so do I(not bibs haha). I need advice. I know a few of you had your little ones on soy formulas.