Dilation check ??

So I have the same ob my sister went to and she delivered this July and I went to some of her prenatal appts with her and ob said they don't check the cervix until 38 weeks, my appt is Friday and I'll be 35 weeks almost 36, if I ask her to do it is it her choice ? Or can I request it be done considering I was at a 3 at 34 weeks with my first AND I've been having blood/ pink discharge here and there and am feeling pressure down there. I know you guys don't know exactly but has this been the case for anyone else and what happened ?