I'm 27 years old. I've been on the contraceptive pill for 6 years. 4 1/2 on microgynon 30 and 1 1/2 on loestrin 20. I weigh 10 stone 7 lb and am 5 ft 3in. the past few months my periods and have been much lighter and have only lasted 2 days and then this month i haven't had my period at all. I've taken 2 pregnancy tests and they have both been negative. What could be wrong with me?