I don't know what to think. I am 47 yr old and worried cause my last period was Jan 2 2016 and haven't had one since. My normal cycle was 28 to 31 days. Never missed period except when pregnant. I think I ovulated late in December due to being on antibiotics. Only had sex once on Dec 30 then period started 2 days later. Only symptoms are acne, sore breasts, a little nausea. Have taken 4 HPT plus 1 in doctors  office and all negative. Don't know what to think? Help