From what you describe, you sound like a typical patient of mine! About 4 percent of women never can have an orgasm. "Orgasmic dysfunction," or difficulty with orgasm, is reported in 9 to 27 percent of women. Sixty to 80 percent of us cannot have an orgasm with intercourse only; we need more direct stimulation, whether manual or "battery powered."
There are lots of reasons for "dysfunction," including neurological disorders, post-surgical complications, endocrine or medical disorders, side effects of medications or drugs; most often the reason is sociologic or psychologic, which includes everything from unsuitable stimulation, poor relationships or communication, history of sexual trauma, and more.
And as we grow older, vascular and hormonal changes don't make orgasm any easier.
If the vibrator you're using isn't quite doing the job, you might trade up to a more powerful model. We've chosen the vibrators we offer at MiddlesexMD (most rechargeable instead of battery-powered) in part because they have stronger motors, which equals stronger vibrations and more sensation. Take your time and focus on arousal as well as the "end game." Even if you're not experiencing dryness, a lubricant can encourage more touch and playfulness. Warming lubricants or oils can also increase sensation.
Perhaps the most difficult advice to follow: While orgasm is quite lovely (and good for our health!), making it a required outcome of intimacy can make it more difficult to achieve. The more you can focus in the moment, on each sensation and touch, the lower the obstacles!