Breastfeeding with teeth

My son is 9 months old and would use his gums to bite down on my nipple a few times and I told him no and he hadn’t done it in awhile. Now he’s got his 2 bottom teeth and omg he bit me twice today. Those little suckers are sharp. I screamed ouch! He looked at me all upset about to cry. I feel bad but omg it hurt and caught me off guard. I’m scared to nurse him now. I only nurse him through the night. I pump the rest. I’m too lazy to pump at night because my room is upstairs and I would have to go downstairs multiple times just to store my milk. Idk what to do but omg. Idk if I can take it one more time. He bit down hard. How do I stop this behavior?