So I've missed my period about 3 or 4 times. I've taken multiple pregnancy tests and they've all come back negative. Before this I had a continuous menstral cycle for a year due to a birth control implant, following that I was on the pill for about 3-6 months and it regulated my period but since I've been off I stopped my periods and have not  been able to get pregnant. Me and my husband have been trying for over a year. I'm young and in good shape, should I be worried?