Shortened cervix

Looking for advice or maybe encouragement I guess. I'm 18+3 weeks with mo/di twins. I see the mfm every two weeks. At my 16 week appointment my cervix was a little less than 4cm, but this week at my 18 week appointment it measured 2.8 cm. The mfm said if it goes below 2 we'll talk about our options and what we're going to do, but she didn't mention anything about any restrictions as of right now. But I've done research and I'm freaking myself out with all the stories I'm finding. Did anyone else experience this and make it to the end of their pregnancy to deliver healthy babies?