Help! Trying to figure out breast 's bottle...

My son was born on 10/9 at 35w 4ds. He was in nicu for 10 days due to respiratory distress. He started taking a bottle about 7 days in and then we tried breast as well. I was only able to breast feed here and there while he was in nicu. He has a good latch but he tires out easily. He could latch for 15 minutes but then he is completely asleep and it take a lot to get him back up to try the other breast. I need to pump after feeding since we dont know if he is getting his adequant amount from strictly breast. I am only producing anywhere from 30mls to 40mls each breast / pump session. Combined it is a little over one feeding. I know he is supposed to pull more milk than a pump but he doesn't seem satisfied sometimes after so we give a bottle and he drinks it all. My supply was slowly getting better but I feel like I hit plateau.... I pump every 2 to 3 hours and have a medela PISA and am trying to eat as much "lacation" foods as possible.

I am so torn with what to do. Do I exclusively pump and try to keep up with him and bottle volume or do I breast feed on demand around the clock and pump..... I'm afraid if I don't breast feed my supply is going to tank...