supplementing

Vanessa
So I know this may br a silly question but I'm a BF mom pump and nurse. My son is almost 2 months old and obviously drinking more and more but my supply isn't keeping up with his eating. I don't want to supplement but I feel right now that might be the best thing to do. But I'm not sure how to supplement...do I do it after he eats and seems hungry still or if I don't pump enough give him the supplement? Comments please! I'm. FTM so all this is new to me!