Implanon/trying to get pregnant after it

So I was on the Implanon for 4 years and have been off now for 1 year and for some reason I have tried to get pregnant after being on it and we try all the time and nothing ever it's been a year that we have been trying and we're both clean nothing wrong regularly periods every month I have had 3 kids already but want one with my husband has any one else had this problem using implanon?????