Formula intolerance?

I am breastfeeding but having to supplement with formula and we have been having a heck of a time trying to find a formula that agrees with our 7 week old babies tummy. She gets so bloated and gassy and just angry. At times she appears to really struggle to poop and cries out in pain, is all clenched up kicking and squirming about. She even wakes up screaming in pain at times. It breaks my heart to see her so unhappy & uncomfortable. My Doctor says as there is no blood or mucus in her poop it isn't an allergy, but surely this can't be normal. We have tried 5 different formulas (including lactose free) and found Gerber Goodstart liquid to be the best so far, but she is still having these symptoms daily. Has anyone else had this problem and what did you do?? 😢