Breastfeeding at night

Help! My 3 week old baby is sleeping a long time throughout the night which is awesome! But since he doesn’t breastfeed I wake up and am miserable! I was pumping some throughout the day or night only if I couldn’t breastfeed. (I was having to for a while to supplement because of some issues my boy was having). My doctor told me I didn’t need to pump at night anymore since he was sleeping. He sleeps 5-6 hours in a row consistently. Last night he slept 8.5 hours. I woke up today feeling a lot of pain. I had leaked a lot and my chest was completely hardened. It felt like a rock. It was throbbing and tingling and super sensitive to even slightly touch. After he fed it felt a little better but It was rough for a while. I don’t want to have engorgement every morning and end up with mastitis. Any advice?