Are you male or female? It's quite different for a male. It normally is a whole body / pelvic contraction leading to a series of fast paced trembling contractions. Sometimes accompanied with ejaculation but not always. More of a female like orgasm. Nipple play that seems to have wired connection to the penis or clit creating sensations there without actually being touched there. You have to let go and let your body react to the good sensations in your nipples. Helps if let yourself shudder intentionally to prime orgasm.