...Masturbation? (sort of embarrassing)

I've been masturbating for as long as I can remember. I must have discovered it on accident as a child, (no, I do not have any history of sexual abuse) and it's been a regular, daily part of my life since. The only issue is, I have only ever been able to orgasm from one thing: humping/grinding. I can remember in elementary school pressing myself against my chair and moving in a circular motion to reach climax multiple times a day, and the memories of it now are completely embarrassing! But that's just always how I've done it. I am now in a very serious relationship, and I love my sex life, but only because of the emotional satisfaction I get from it. My boyfriend has never been able to make me orgasm, and it's something that I would love to experience by his doing. We've tried clitoral stimulation, fingering, etc which all feels good and makes my legs shaky, but I haven't actually came from any of it. I'm afraid to admit to him how I get off normally, because it's odd and embarrassing and awkward and I'm at a loss on how to make our sexual relationship equal. Any tips or advice for me? Thank you in advance! :)