How about double penetration?
If you are too loose then I can't imagine that fisting will help. Maybe take a break from anal for a bit, and do some butt exercises to tighten up. It could help
So your bf suggests you stick to fisting. Was it fisting that got you this loose? From what I'm told, double penetration doesn't give the tops a wide range of motion but it would certainly fill you with a girth of cock and stuff your loose hole.
I do know someone who had his asshole tightened surgically -- in the process of suturing up a tear -- so it can be done.
In this case I would believe going bigger is not better.
You have to give things time to go back to "normal".
If your guy thinks you are too loose though, it is probably because his dick is too thin and needs a scapegoat.
I have yet to find a hole I could not fill and been in a pussy that has popped out 3 large babies.
So tell him to fuck you with his pencil dick, then bend him over and get yours too.
He has a nice dick. I just been a real slut, taking guys' dicks all the time. My own fault. I might look into that surgery though, thanks.