I stopped taking birth control after 6 months on it and had unprotected sex the next month while ovulating. Now I'm 2 days late for my period, but I've started having some very light, brown spotting. Is this a common start to a pregnancy? What are the chances that I'm pregnant since I just stopped taking birth control.

It is common, light bleeding, but it also may be your period just being strange, especially coming off the hormones, however, it is possible that you can get pregnant even while taking birth control, so yes, you may be pregnant. Take a HPT to find out.