There are no guarantees in life.
As it stands, you are pregnant with a wanted baby, that you've been trying for a long time for, trying so much you are on fertility drugs. At your age, given the struggle to become pregnant, you might never become pregnant again.
Throwing away that chance, along with the wanted life you carry within you, because you cannot be '100%' is madness and something that you would likely regret for the rest of your life.
The chance of you harming your baby through your drinking is absolutely tiny, but the chance to you harming it by going through a termination is 100%
It might help if you try to recognise that the issue really isn't your drinking, it's your anxiety. If it wasn't drinking, it would likely be something else - forgetting your folic acid, or eating the wrong cheese.
The biggest danger to your wanted lovely pregnancy at the moment isn't your early drinking binges, but your anxiety. I'd suggest you need some urgent mental health intervention to help manage your anxiety.