Only orgasm during 69?

Ok so me and my bf tried 69 yesterday for the first time, with me on top, and both times we did it, he actually made me cum, which was really surprising to me bc normally I don’t cum during sex. Although one time i was on top of him and he was wearing a ribbed condom and I started to feel the building pressure slowly, but had to stop bc i got too tired. My question is, why did i orgasm from 69, is it bc his tongue is at a different angle? And how do I orgasm in other positions like missionary as well?