I am 20 years old and am wondering if my cycle is normal. It averages only 21 days (ranging 18-24) from the start of one period to the start of the next. My period usually only lasts 2-3 days (one day heavy, one or two light), and I don't have cramping or any other adverse symptoms. It's certainly nothing to complain about, but I'm wondering if it's normal or if I should ask my doctor about it. I'm not on hormonal birth control