Sudden return of period after 2 years with iud. Did it fall out?

I've had my iud (mirena) in for 2 years and have been nursing my baby girl for the duration. No trace of a period up until last month. I presumed that it was because she wasn't nursing as often, but now I'm scared that it might have fallen out! I checked for the strings for the first time and can't feel them! Did it fall out?Sudden return of period after 2 years with iud. Did it fall out?
if you cant feel the strings then you are bound to be worried,

best check with doctor for reassurance