All_girl, thanks for sharing this. You mention two very important things. You can only orgasm if you keep on stimulating yourself. If you stop and give up, you will not orgasm. The first time all sorts of strange feeling will go through your body and you should not be scared of it. Like you mention, your body can twitch and shake uncontrollable, shaking your bed. Your breathing may become very rapid and shallow and your heart will beat like when you are exercising. And just before orgasm, you can experience a feeling of agony in a very good way. The sexual tension will be so high that you will crave relief. That relief comes as the release of sexual tension during your orgasm, shaking, grabbing and gasping included.
The other thing is that since we as women do not teach each other how to orgasm, masturbation porn can be useful to teach us. And during arousal, it can help to watch or read something erotic. You can also fantasize about doing something or being with somebody.
Masturbation is a healthy way to deal with sexual urges, it is healthy and good for you, and it play a huge role in preventing relationship and sexual problems later on when you become sexually active. It also serves to educate you about your body and sexuality.