How do I know if I had an orgasm?

Kelsie
I've never orgasmed before even though I've had sex and masturbated. But today I was playing with a shower head and got super close. My body tensed up and I couldn't control my body but this happened five or six times.... Is that what the orgasm is or is that just the build up, and the orgasm is something completely different? Please help... I'm still feeling shaky and horny so that makes me think I didn't cum, or do people feel this way after an orgasm?