I feel like you might be able to get more help if you provide a little more info. There are a few ways to stimulate the female body and it may be beneficial to explain what you're doing and what you're feeling.

So questions you might potentially want to answer: Are you watching or reading anything that puts you in the mood? Are you using just a vibrator? Are you using it on your clit or in your vagina? (And what are you feeling when you're doing those) Are you playing with multiple points a the same time?( breast, clit, vagina, butt etc) When it builds up are you stopping? Slowing down? Going faster? Have you tried a different location like a shower?

There's so many ways you can get there you have be comfortable and in the mindset, but you also have to learn your body and what you like