It takes time and patience. You’re probably rushing yourself and pushing to orgasm when that’s exactly what you can’t do. It doesn’t work like that.
Set aside an hour or two where you know you’re going to be completely alone. Take a bath, relax, get yourself into the mood, and work yourself up slowly. Guys have it easy where they can just pump themselves into a frenzy for a minute and boom! Girls need more time and it relies a lot on your state of mind. It’s not just what you’re doing, but what you’re thinking, and what you’re allowing your body to feel.
Keep experimenting, focus on relaxing, and you’ll make it happen!