Something I didn’t see mentioned here is hardness. Size won’t do much for a woman if it isn’t hard. And hardness will to a lot for a woman if the guy is average sized. You might try something like Viagra to “enhance” your erection and read up on angles of attack so that you bump her clit with your pelvic bone while rubbing the head of you dick against the “G” spot area.
One of my favorite postions is for me to stand and have my wife hang from my neck while I support her legs. In this postion, I go so deep that I can actually push the head of my dick inside her cirvix. In any other postion, I can only massage it. For me, massaging the cirvix is what makes my wife cum. Hope this helps.