Baby formula

So since day one my 7 week old has been using Similac pro advance she never had a problem with it had good poops rarely ever spit up or not gassy. Then around 5 weeks old she was spitting up a bit more. So I accidentally bought Similac pro sensitive and she hasn’t spit up doesn’t have much gas and so far she’s had a few poops (2-3 poops can’t remember, with one day of using it) (with pro advance she had maybe 6 poops a day) so not as much as she did with pro advance so I hope shes not constipated, I will look out for that as we continue to use it but if she still doesn’t poop as much I might go back to pro advance even tho it makes her spit up a little. But I’m also wondering if I should try Similac pro total comfort since she does spit up but idk it’s not like she spits up a lot so we’ll see. Any of you have experiences or a preference with your baby formula?