Hi! I am 29 years old, 190 lbs, and 5 ft 6 in. I am on Metformin for insulin resistance and I have been on it for almost a year with no changes to my period. I have been regular pretty much since my 3rd child was born in 2007. My last period was right after Memorial Day and I should have had my normal period either the last week of June or the first part of July and I have not had it. My husband had a visectomy 3 years ago and I am wondering if pregnancy could be one of the causes of this. I have had nausea that comes and goes but nothing severe, minor headaches, and lower back pain. I have also taken a pregnancy test and it came back negative. Can you help me get some idea on what may be going on? Thanks!