Well, you could have fibroids but that is kind of a separate issue than the positive tests. You may have had a chemical pregnancy early on in which you were early pregnancy when tested and then around the time of a period or shortly after, you started bleeding like a period and it was actually a really early miscarriage. In the olden days before home pregnancy tests, women never even knew they were pregnant. That may have happened and this may be round two of pregnancy. The moving in your stomach --- not sure if that is really happening as in a baby moving. That feels like flutters. I actually didn't feel my baby move until I was around 20 weeks because it is so faint and subtle. Now, we do have a pulse in our stomach as a major artery runs through there. Could that be what is happening?
So, false positive tests are rare. It's triggered by reading HCG. That's the hormone a fetus creates. It does happen once in a blue moon though. Are you reading your tests right away or letting them sit?