Increasing my supply… trying everything

Hi everyone. My son is now 3 months on Saturday.

He was Exclusively breastfed for a few weeks, then we were told he has a tongue tie and should introduce formula Bcos he is not able to get enough milk himself. He really hurt my nipples at that point I couldn’t even pump, I was leaking and engorged. I started feeding less and less until his tongue procedure, then I wanted to breastfeed again and realised I barely have any milk left. My lactation consultant advised me keep putting him on the breast at every opportunity but when he is getting his usual feeds and I put him on the breast he just throws up, and he won’t stay on the breast more than a few mins Bcos there is not much for him to get, he gets frustrated. I rented a hospital grade pump, even tho I have an Elvie double pump, thinking this would really help and I should power pump.

This is not helping me, I’ve powerpumped for some days and not seeing much on an improvement.

Does anyone please have any advice… how do u increase your support when nothing works?