Never had an orgasm before. Ever.

So, I'm 20 years old and have had a decent amount of sex. I've tried many things but have still never had an orgasm. Ever. I feel like I've gotten close before, but then when I feel like something is finally going to happen- the feeling disappears almost instantly. It's seriously so unfair. Has anyone got any advice for me? It's so frustrating and frankly, sad as f*ck