Baby position

I'm 35 weeks and my baby's head is right at the entrance of the cervix. As in my cervix is closed but when the dr goes to check she can feel the skull in my vagina. Why isn't my cervix opening? I know I'm a little early but I can't help but think she's ready to come out. I'm supposed to have a c section in 4 weeks and I don't want to go into vaginal labor beforehand and have it be too late for a c section. Should my dr be checking because he hasn't checked my cervix at all this pregnancy. The hospital did at 33 weeks. But that's it.