Any suggestions?

So whenever my bf & I have sex.. I find it's really hard for me to have an orgasm. I prob came once since we've been having sex. (New relationship) .. any tips on how to reach orgasm faster? Sex is amazing, his penis is a really decent size.. we do oral on each other as well but I just find I'm never orgasming.. & we have sex for long lol.. he always lasts long tryna wait for me to get off lol..funny thing is when I masturbate I can cum in like 2-5 minutes lol