Aromasin is the best AI. Chances are that yours was underdosed given you were using 20mg ED with only a moderate amount of aromatizing steroids. Try 25mg ED of pharma aromasin and adjust from there. If that's still inadequate, then perhaps you're one of the people who just don't respond well to aromasin, in which case you should switch to arimidex. Letro is a last resort since it's a harsh drug.

Nolva can be used to stop estrogen from binding to the receptors, but it will not lower estrogen or reverse gyno. All the best mate.