Advice needed please!

My son is 5 weeks old. I am EBF. We have been wanting to do a bottle before bed to make sure he is going to sleep full. He ate 3oz the first night that we tried it so I’d like to keep giving him 3oz in the bottle. I pump right before feeding him at bedtime but I am only able to get out about 2oz now. He only eats from one boob per feeding since he feeds for about ten minutes total so when I pump for the bedtime feeding I only pump the boob he should be eating on.

Should I be pumping the other boob that he does not eat from every feeding?? I feel like my body is used to him only feeding on one now but I’m not sure if that is going to or already is messing up my milk production.