Comming off the contraceptive injection

Hey all we trying to get pregant with our 2nd child but having really hard time off it . I come off infection on 4 dec 2012 after 2 years been on it since comming off it I had really bad period really heavy bleeding but can't seem to fall pregant has anyone else been this way and how long did take urs to consive . Really want other child as we have Six year and dont want to wait much longer z