What Causes Long Periods, Intermiitent Discomfort During Sex And Thickened Cervical Cavity?

Hi, I have continued to have periods (though not as heavy) despite having a mirena coil put in 9 months ago. I still bleed for 10 days to 2 weeks intermittently and some discomfort during intercourse. I have also noticed intermittent discharge and discomfort. An ultrasound showed a mixed echo thickening in the cavity of the cervix (14mm). Haven't had a smeat test done yet but could this be a cervical cancer?