Trust me girl you would know. As your about to reach orgasm, your body starts to shake, your heart rate increases, you start sweating more and breathing heavier and then all of a sudden you get this exciteable pleasureable feeling....and thats an orgasm. Don't worry you will know when you have one because it feels too good!! Take care =]
You probably would know you would feel like a sensation go through your body and it feels good.