Is it possible to start pumping again to store breast milk?

I stopped pumping around 3 months because I wasn’t working and just decided not to for some reason. Now I’m working 3 days a week, 5 hours at a time, and would be nice to have a little stash. My son won’t take a bottle though at all so we had been using the stored milk to try to get him to take it and have used almost all of it. If he ever starts taking one I won’t even have any to give him! Is it possible to get started again? How? When should I pump without jeopardizing my sons schedule? He still eats twice through the night as well.... Thanks!