Depo jab

Kezz`
Hello I was on the depo for 2 years my last jab was in May last year(2015) should of had it again in August but me and my boyfriend way a baby it's been 6 months still no period no spotting nothing. I was doing ovulation tests and I had positives on 25 Jan but nothing since and pregnancy tests are negative. Has anyone got any advice on how to get my periods back to normal so we can track and hopefully fall pregnant :(