How can I reach during ?

I have never reached during , except with the help of a bullet vibrator. Don't get me wrong, it feels amazing, but I can't "reach the high note". I've heard its easier when the girl's on top so i tried different positions, but truthfully I'm bad at being on top. I can't get the rhythm right. My fiance and I mostly just do missionary, and I would like to be able to in that position. I've also tried kegel exercises, and it's tighter for him! But it doesn't seem to make much difference for me. Any suggestions? Are there some women who just can't solely with ?