Any ideas?

So my period started Feb. 5th and ended on the 8th. It was heavy for like two days and then spotting. So fast forward to this morning I got a faint positive on a pregnancy test. I’m on birth control pills and haven’t missed any. How could I be pregnant so soon? This makes no sense to me. First picture within the time frame and the second is dried for reference.

*also I’m already planning on taking more tests within the next couple days and going to the ob. Just wanting opinions. Thankss❤️