You will know when you get an orgasm. You may experience not being in control of your body and your body will spasm and you may just feel wild with elation. You will not be able to control your body spasm and jerks.
With the nipples feeling hard and your vagina getting moist is to do with being sexually stimulated.
Women can experience multiple orgasms. That means a few at a time, 1 after another. A man, once he has ejaculated (that is in effect his orgasm) has to rest and allow his body time to make more before he can have sex again.
You will know when you have had a good orgasm. You can get little mini ones when the uterus will have little jerk spasms.
You may have had a mild orgasm. They vary in intensity. Usually your heat beats fast and your chest gets hot and nipples get hard.