my cervix is still measured at 2 1/2

doc. said they want me at a 3 long as i dont hit 1. ftm huh i just dont understand. i have not been put on bed rest or anything. theyre telling me im great baby great and everything is ok. i dont know what to do. ive spent my first 3-4 months on amoxicillin due to UTI 3xs a day. kno they want me to take 1 a day til i have the baby😔😞