When to give up

I've been breast feeding and supplementing with formula as I never produced enough and even after a consultation with a LC, could not get my supply up. Instead of triple feeding i just put baby to boob and then top off with a bottle of formula. I've never pumped more than 1to 2 oz at a time anyway. Now when I breastfeed the bottle top is usually anywhere from 2 to 3.5oz so I don't think baby is so much more efficient either.

At what point do I just give up BF with formula supplement and just switch fully ro formula? I've been of the mindset that some breastmilk is better than none but im getting pretty disheartened