I read the manga along when the anime aired and i dont read every chapters just some that i really want to compared to the anime. So i think i probably read about 20-ish chapters with the last one being chapter 36.

For the difference i've noticed, the manga has nudity and more explicit than the anime. The anime also changed the order of some chapters which i think worked really well. There's some content that they didn't adapt but mostly its either not important (mostly some characters interactions) or some more clue that made some things more obvious. The anime also added some original things like that strap that juuichi has from the couple which for me make the emotional impact. Ofc the pacing also feels different due to the different arrangement but its still good. The only pacing i feel like the anime made way better than the manga is the content for episode 8.