Why have I never had an orgasm and how do I know when I do?

So I am always wondering why I can never get myself to have an orgasm. I have tried so many times to pleasure myself but it justdoesnt feel good! I have tried so many different areas and I just don't know why. I haven't had sex for 3 years and even when I did I never got one then either. One tome with my bf when we were having foreplay I thought I was having one, but people say that when you're having one you'll be confident in knowing that it was. And I'm not totally sure. What's the deal? Why can't I have one? Nothing seems to work, even though I get turned on very easily