There is nothing wrong in trying to find ways to orgasm and sometimes that search can be an adventure itself. But you have to remember that some women just can't orgasm from penetration alone - its basic anatomy. The G spot (its not a spot at all but an area) can be stimulated to orgasm, but once again, it doesn't work for every women. You can try to have a G-spot orgasm from different positions like doggy or cowgirl sitting up straight. You are go for the clitoral orgasm in male superior position where the man is positioned further up to have more clitoral stimulation. Also girl on top leaning forward with a slow grind can help. The easiest is to stimulate yourself or have your partner stimulate you. This works well in doggy position.
There are no vitamins or stuff you can take for this, just practice. When women go into menopause, their estrogen levels drop, this can cause less sexual sensations, not more.