Whats going on?

I was due my period on 19/11/15. And still havent had it now 12 days late. Ive taken a pregnancy test and its negative also blood tests with my gp for HGC levels and it came back negative, this happened with my first little girl and it took me a while before a positive test, and in May i had a miscarriage so im a bit worried and not sure what to do or think. Any advice wouls b so grateful. Thank you.xx