What the heck?! Even with a friggin period of the 15th it would have still been too early too see. Although, your HCG would be higher. Ummm I'm guessing you haven't lost it yet, unless you were bleeding. Let's say your period was the 20th. Two weeks later you would ovulate (in a perfect 14 day world) then you have implantation which is typically 7 days but can go to 10-14 days. So! If you ovulated a few days late, and then implantation took a couple extra days. It would be just a couple days ago that it nestled in your uterus. Making the 11 HCG perfectly normal. Your body usually has about 0-5 hcg naturally! And doubles every two days. Unless you're bleeding, I would say congrats! And test in a few more days to see the lines get darker
hope that helps