I have a very hard time with vaginal orgasms as well, when masturbating. My body needs a very specific position. I also have a friend that can only have vaginal orgasms while she's in the girl-on-top position.
Work with your body, see what it likes. Try different positions; doggy style, being on top, on your side, standing, etc.
Sometimes we also need clit stimulation, so try that as well when you're using a dildo/vibrator.
Also, sometimes my body wants a dildo rather than vibrator, so maybe try one of those instead? Just keep on trying and you'll eventually find out what your body wants/likes