Breastfeeding Bottle Nipples

My baby loves nursing but he still has trouble transferring milk at 5mos. We use bottles to get him fed enough but lately he’s rather only eat bottles while sleeping. We were using Medela Calma nipples which worked great and he could nurse fine but then they really bothered him with gas. So we’ve been using Avent Natural nipples and he’s just started clamping down while nursing and biting. I don’t think it’s purposely done and I believe it’s because the Natural nipples (not the Natural Response) let out milk when squished. So he’s just doing what he does while drinking a bottle. Also I’ve noticed his latch get less suctioned since switching. So what can I do to get a bottle nipple that works with suction instead of squishing/biting? And how to help him get back a good latch? I’d go back to the Calma if he didn’t get so gassy poor guy