head help!!

I reaaaally need bj help. The first time I blew my bf was the first time i had ever given a blowjob. Afterwards, he said that it was incredible and he couldn't believe it was my first time, but he was also pretty cross faded when i was doing it (as was I). I was super nervous to do it the second time because we were both sober, and his response after wasn't as enthusiastic as the first time. I actually apologized after he finished and he was like what no don't apologize that was great. I felt like i sucked at it (no pun intended lol) and he was just telling me that it was good so he wouldn't hurt my feelings. i have a pretty bad gag reflex and I always overthink it and feel like I'm biting him or something. He asks me to do it all the time and I try to avoid it because idt im good at it, but i feel bad bc he always goes down on me without me even asking. pleeease help me