Late Period, Negative Pregnancy Test. Reason?

hi i am 46 years of age and last year my gynie removed my loop and suggested i do not need to have another one inserted,as i am past my child bearing age,my periods have always been regular and for 7 days after the loop was removed it was only a 4 day cycle this past year with my period being a week late or early,but now i am 2 weeks late and very anxious,had a pregnancy test done in my doctors office this afternoon which was negative and i was extremely relieved,but still worried as to why i am missing my period my last period was 01 June for 4days,my eldest is 24yrs and my baby is 19 years,i am ready to be a granny not have another child at this late age,as i will defintely be going on retirement at age 55,please advise