How do I ask him for more head?

I've been in a relationship with my boyfriend for almost seven months now, he's only eaten me out twice (once when we first started having sex and another time when we were both pretty drunk) and I think he thought I wasn't enjoying it because I didn't orgasm. Both encounters lasted less than five minutes each. I'm not great at asking him to do certain things when it comes to sex.  it's not that I'm afraid to, it's just that hes my first and he's pretty experienced. I really want him to again but I don't want to just push his head down there. I'm super bad at this!!! How do I ask him to go down there more!