never had an orgasm

hi! i have never had an orgasm before. i’m not into playing with myself, i just don’t like it. when my boyfriend plays with me, i sometimes feel like i’m going to cum, but i don’t know what that would feel like. the feeling is just really good and my legs start to give out. is this what that feeling is? i feel it quite often, but i never end up orgasming. i feel like maybe i start to get too tense when the feeling happens, and that’s why i can’t. any tips on how i can just let it happen.