Preterm labor question... high risk


**posting here too** (sorry πŸ˜•)

So as I've said before I am high risk for preterm labor. Both of my other children were born at 29 weeks. I am now 28w and a few days, so the 29 week mark is almost here and I'm getting a bit nervous.

They arnt sure what caused my other 2 preterm births and I wasnt be monitored then. This time around they are checking my cervix every 2 weeks and this past Monday everything looked nice and long. But they arnt sure if it was because of incompetent cervix or if my uterus started contracting early?

I guess my question is, since my cervix looked long and good Monday does that mean I have a pretty good chance of making it past 29 weeks this time? How long does it take for the cervix to "thin"? Could it happen suddenly or does it take a few weeks to happen? If my uterus does start to contract can that thin my cervix pretty fast? I mean to ask all this at my cervix checks but I always forget my words and get excited that my cervix still looks good.

So hoping maybe you mama's have some insight on this. Trying not to worry, but as 29 weeks gets closer its getting a little nerve wracking.

Thank you!