Hi....iam 18 Years Old.every Month I Used To Get Periods

Hi....iam 18 years old.every month I used to get periods but this time it is extended fir 12 days and then 2 times I did pregnancy test at home day after day both the time it resulted positive but after testing living one day I got periods not heavy light.....iam I pregnant???? Iam confused would you please help me out of this