confusion with milk supply

Rachael
Hi everyone I ran into a problem with my milk I think? My 3 week old is constantly on the boob for comfort and get snacks each time as well so is not always hungry, but I milk supply never seem to go up my boob feel constantly soft and I'm worried I drink heaps of water and eat good food and I am not stressed ( not too bad with this ) 
Does any one have any suggestions what I can do