Orgasming with a toothbrush

I've been masturbating with a toothbrush for years, however, I've never managed to orgasm with it or anything! Although when I do it for a longish time I begin to feel my vagina pulsing I guess. I don't know if this is a orgasm or what.I can't get a proper vibrator as I'm only 15. Please give advice on how to orgasm with a toothbrush. Thank you x