Confused?!

So last week I took a pregnancy test. It was a faint positive. A couple days later I started bleeding like I would for my period. I went to the doctor and had some bloodwork done and the results came back as negative (levels under 2)? So I assumed I had just had a chemical pregnancy. Well, just yesterday (a week and some days after all this happened), I took a test just because I felt like it, and I left it and forgot all about it until I got home hours later and there was a line. Twins do run in my family, so is it possible I was pregnant with twins and lost one and am now showing more positive because my levels are higher??