It certainly sounds as though you’re experiencing sexual arousal and excitement. You’ve found a few things – masturbating, reading erotica, and writing erotica – that help take your body (and, I would guess, your mind) to an erotic place where you feel ready and able to open yourself to sexual arousal.
Whether or not you will experience an orgasm is not something I can tell you. Nearly all people are capable of orgasm, so it’s very likely that you are too. Some sexuality educators and therapists encourage people to focus on sexual pleasure and enhancing arousal rather than putting pressure on oneself to orgasm. As it turns out, orgasm appears to be more likely when the focus is on pleasure or arousal.
You might try exploring your sensations. When you find your back arching and sensations arising in your vagina, you might try relaxing and focusing on the sensations. If you are open to it, you could consider fantasizing about someone or something exciting, pleasurable, or romantic.
No matter what your sexual orientation is, know that people sometimes fantasize when thinking about either same- or other-sex partners. And some people fantasize simply by focusing on their own bodily sensations, such as feelings of warmth, fullness, tingling, build-up, pulsating, or waves of pleasurable.
There’s A Toy For That
If you are interested in using a vibrator, you might try a multi-speed dial that offers various intensities – many silver bullet vibrators are affordable and offers different speeds and intensities, so that you can explore and find sensations that feel enjoyable to you.
If you’d like to explore orgasm and arousal, you might like reading the book Becoming Orgasmic. It’s written with a gentle style that encourages experimentation, exploration, and getting familiar with one’s own body, emotions and feelings. It also includes a good deal of fact-based information that may help you to feel educated and empowered in your own sexuality.