being told while on depo!!

i was told being on the depo if you are even a day or a week late for your next round of shots you can conceive right away but then you hear all these ladies who are months to years off the shot that are having so many issues. i being one. i have been of them. i have been off for a year in december of this year i have all the symptoms of me being prego like my last 2 pregnancys. but all my tests keep coming back bfn!!!! i really want to have another baby with my hubbie. i feel so useless...