Orgasm??

So I’m 15 and I masturbate pretty regularly and every time I reach what feels like a climax. My whole body tenses up and stuff and after I stop or it’s over or whatever then then I just kind of have to stop cause it feels kind of weird. I don’t know if it’s actually an orgasm because I feel like it happens way too easily (like every time and it doesn’t take very long at all) but I just don’t know. Is it?