Lighter periods with copper coil

[RahRah32]

I have had the copper coil for 18momths now. Up until last month I was having very heavy, painful periods lasting 7-9 days but regular as clockwork. Last month my period lasted 3 days and was very light, this month 2 days and even lighter. Has anyone else had this happen? I'm still getting menstrual cramping but a lot less bleeding. I'm wondering whether to go to the GP (or do a pregnancy test 😳)