So since my doctor has told me NOTHING. When will they start checking my cervix ?

mine doesn't start checking until 38 weeks. some don't check at all until you're in labor

So that's not something they HAVE to do then ?

It depends on the doctor. Some start checking around 36 weeks and some never do. Mine never checked but I never asked her to because i didn't think it was necessary. I'm sure at this point if you ask they will probably check for you at your next appointment.