Exclusively pumping to nursing

I have been EP since the beginning. My baby was 4 weeks early, and didn’t have a strong latch at first. I found that pumping and then bottle feeding worked best. He has always loved to suck. Now that he’s 7 weeks, he has a strong suck. I have been killing myself with this feed/pump schedule every 3 hours and figure it’s easier to just breastfeed. I’m at my end with pumping, but feel so bad because I want him to have breastmilk. We tried nursing a few times, and his latch was painful, and I kept giving up and going back to pumping. This is my last ditch effort. I have a few questions. 1. How long will it take for my nipples to adjust to the stronger suck? 2. Do I have to pump after every feed? 3. How do I know he’s full? Tonight I went back and forth from boob to boob 3x each because he was letting go after 5 minutes but clearly still hungry.

He’s passed out, and seems happy.