Spotting, Pregnancy, and the Pill?

I have been on the pill for 2 years. I have never had any spotting or breakthrough bleeding during the month. I always start and end my period on the expected days. However, this month I started to bleed two days early. It has been very light and not its normal color. I am worried it is implantation bleeding. I have also cramps and tender but i also get these symptoms with a normal period. I did miss one pill this month but i took it the following day. could i be pregant? when is the earliest i could take a pregnancy test? I know in two days I will have more info based on whether or not my real period actually starts... but i want to know sooner! im so scared!