I need a little insight. I haven't had my period in a few months, and I've had nausea but no vomiting. I've been peeing a lot more than normal. I've become extremely exhausted over the past month, and I've been having some constipation. I have constant headaches. I'm slightly bloated, but my weight hasn't changed at all. I thought I might be pregnant, so I took 3 tests (I used 2 different brands), and I'm definitely not pregnant. Can anyone think of what could be wrong with me?