Depo shot

For any of you who have taken depo (birth control shot), how long did it take you to get pregnant and how? my mother said she got pregnant the first week off. I only had 3 shots (9 months), I don't have money so instead of all those fancy test and such i take Vitamin B complex and Fish oil to hopefully be more fertile. I've been off for 2 1/2 weeks now and have bled a couple days. Any advice??