Period or normal 4week spotting

So I still haven't had my period and I downloaded a pregnancy app and it said that I'd be 4 weeks and two days pregnant if I am pregnant.... It also said that I should be expecting swollen breasts (or tender) which they are a Lil and spotting I went to go pee and when I wiped I had brown stuff mixed with a Lil bit of blood it's not heavy and I'm not cramping so has my period finally started or is this just part of the pregnancy!? ... Has anyone else experienced this!? I don't wanna put my hopes up for nothing...