I think I can't orgasm.

I'm still young, late teens, but I've been sexually active for a while and as hard as I try by myself or my man tries, I never ever orgasm. I'm beginning to think I'm one of those girls who can't cum.

Honestly this is making me really depressed. Has anyone else ever thought they were someone who couldn't cum? Did it take any of you a while to figure it out?

I've tried oral for over 30 minutes and it brought me close (I think) but then afterwards I felt horrible and sad. Stimulation is the same, everything is the same. This is a huge problem in my life right now. Any advice would be a HUGE help