i suggest trying to open your jaw really wide and then give him oral. try this without closing your mouth and sucking. he will love it. once you get that down then try to close you mouth over him, but dont suck yet. Then once thats good start sucking.
i did this and my hubby says he loved it when I barely closed my mouth. Cause I have a small mouth too but opening my jaw helped move my teeth out of the way. but there will be times when you just cant help it
and just practice the deepthroating. it takes time and patience to learn to control your gas reflex. we also found that 69 postion with me on bottom opens my mouth wider. And try give oral backwards...also know as 69 with you on top
theres something about being backwards that helps me