makes the cervix
softer rather than harder. And It would have been easier to insert, though it would have caused bleeding as well. Some Mirena insertions are painful and result in crampy pain. The maneuver of insertion involves holding the cervix, which could cause nausea
and uterine cramps
I would advise you to go for the mirena insertion on the 8-9 day of your next period. This will not only ensure you are not pregnant, but also that the cervix is slightly open at the end of the period, which could make the insertion easy.
Hope this helps.