Help!!!

April

I'm 37 weeks with my 5th baby I go to the doctor tuesday to be checked for dilation but I checked myself today and my finger goes right through my cervix i believe I'm at least 1cm- 1 1/2 when i stuck my finger through i can feel something like it's a hard ball and its slippery i think it's the babys head in the amniotic sac not sure how long it will take to dilate since this is my 5th baby did this happen to any of yall?