It's entirely possible your hymen was ruptured at a younger age without any real notice by you.
When I was 4, a bully shoved me into the community swimming pool. One leg stayed on the ground, the other went into the pool, so I did a "split" on the sharp pool edge.
The lifeguard who pulled me out noticed blood in the water, but couldn't find any cuts on me. I was no longer bleeding, but when my mother came to pick me up, since there had been blood at all, she took me to a doctor.
When I told him what the bully had done and how I had scraped the inside of my thigh on the pool edge, he examined me and then told my mother, "No man will ever believe your daughter is a virgin, because technically, she no longer is."