Best formula for gassy baby?

My baby girl is 7 weeks and has been on Similac Neosure for preemies since we left the hospital because she was 5lb when she was born. She was born at 39 weeks. She’s always extremely gassy and cries and screams when she eats. We’ve tried several different bottles, gripe water, and gas drops but nothing seems to help. Any suggestions on formulas to try? I hate seeing her in pain. TIA