Gassy baby

What formula do you use? my baby is 15 weeks and I just started to slowly introduce formula. (I mainly breastfeed but I give about 8-10 ounces of formula a day. Which is around 2-3 feedings) I use Enfamil gentle ease because she would vomit the normal enfamil. However ever since introducing formula she’s been very gassy and has bad gas pains. Does anyone have any advice? Maybe switch Formula? She’s been a lot more hungry recently and my milk supply hasn’t been keeping up. I’m thinking about starting to introduce baby food as well but I will speak to our pediatrician first.