Blow job?

Iv been with my fiance for 2 years. I don't give blow jobs because I know I'm not very good at them I can't go down the whole way I gag and stuff and I'm not a fan of giving them.. well a couple days ago we did 69 but we tried it m we were both in out sides, for some reason I was able to go down the whole way and he was really enjoying it which turned me on more.. how come when I'm giving him a blow job on his side I can go down farther? Is it becuaue I'm moaning form him eating me out? I heard moaning helps with gag reflexes.. But I am super excited I can finally please him with a blow job! That was one thing I wished I could do becuaue I know he enjoys getting them.