Am I having an orgasm?

So whenever i masturbate it’s nice and I’m enjoying it but then I shake a little bit for maybe four seconds and it feels like I just had a muscle spasm in my vagina. Sometimes I try a different “method” if you will, while I’m in the shower I turn on the bath faucet and let the water fall on me and by the time I’m close or I think I’m close my legs shake and it feels like a muscle spasm again but slightly intense? It feels better and more relaxing but I don’t like the idea of having to shower every time I want to masturbate. Am I orgasming when I feel the muscle spasm? Because if so I’m fairly disappointed... please tell me I’m not fully experiencing it or something because if the muscle spasm feeling is all it is that’s disappointing. :(