Advice on pumping/storing

My son is a little over 1 month old he’s been breastfed since birth but occasionally will ear pumped milk in a bottle when necessary. I return to work in a month and I need to up my stash for while I’m away from him. I usually only pump once or twice a day now, and only get about 2 oz combined from both sides. (Idk if that’s good or bad) and LO eats about 3 or 4 oz when he does eat from a bottle. I do have only about 13 bags of 2 oz milk saved right now. Should I be pumping more or more often? I’m afraid of not having enough of a stash for when I go back to work.