Blowjob

Alright ladiesss I need help/advice 🥲 for some reason I cannot make him cum by giving him a blowjob. Which he wants me to try and make him cum by doing it that way.

He wants me deepthroat all of it but I start to gag, he said the trick is going fast and he said I can suck harder but gently.

He is the only guy I haven’t been able to get to cum what can I do? Also he is uncircumcised