I am not an expert. I'm sure a real expert will be along in a moment. But I can ask the questions I know they'll ask ...
How is his weight? Is he gaining now, with top-ups? How much?
Is he producing lots of wet nappies, and dirty nappies too?
How is his health otherwise?
Did you get really engorged when your milk came in?
There are lots of things you can do.
First of all, getting 5ml after 5-10 minutes is normal. Expressing takes practice. It is a good idea to keep expressing, to keep your supply up with the top-ups and the feeding problems.
Second of all, are you seeing BFCs? Do you have support with feeding? Are you trying different positions, to try to sort out the side he's not feeding well on? (People do manage to feed babies successfully on only one side, but two is easier, I think.)
From what I know, you probably should detach him from the breast when his tongue starts going wrong (put a finger in his mouth to break the suction first, otherwise, it will really hurt). Make sure his tongue is properly down before you let him latch on. He can learn that he only gets boob by feeding properly.
I think some people follow the same rules with the bottle, so he bottlefeeds in the "correct" way for breastfeeding. Could you tell if he was bottlefeeding with his tongue up? Or could you give him the extra formula via a cup, to avoid bad habits like this?