Please help !!

Nichole
so i've been on the Dempo for four years since I had my youngest daughter in 2012 I just recently stopped taking my birth control shot in September on the 1st my last injection was June 2st so I haven't had it since then and I was supposed to get it on September 1st and I haven't, now I haven't gotten a period yet and I've been trying to conceive ..my question is implantation bleeding? how long after would a positive pregnancy test come after implantation bleeding ? Or would it show positive now ? Please help