Truth is you need to find the right formula for your LO. Enfamil A+ is pretty good, so is Goodstart. However they are only good if your LO is good on them. Talk to your Doctor and make sure you tell them all that you see. ie How gassy your LO is, are they spitting up, things like that. It may be the formula it may not be.
We went through Goodstart, Enfamil, and simillac and then found Parents Choise (walmart brand) which was the best formula for our LO. Keep your eye's open in case your LO is milk, or lactose intalerant, or just has a more sensativer tummy.
No your not being to obsessed at all, as much as you don't want to keep switching formulas, you also want one that works for your LO.
HTH