Period is late

I got on depo with my second baby and while on it towards the end I would bleed kinda like a light period sometimes a medium flow. Well I did two doses of the shot and didn't go back for the third dose. Last month it seemed like I got a period because I bleed for almost like a week. And know we are here in the end of March and I haven't gotten a period. But when I wiped yesterday it was a red brownish color so i thought it was implantation bleeding. Because I have also been having cramps. So I took a test and it came back negative so my question is could there be any chance that I'm pregnant. Oh I have been having unprotected sex with my fiance.