28 weeks and short cervix

So at 23 weeks I went for a regular obgyn appointment and I was told that my cervix got shortened from 4 cm 3 weeks before to 1.2 cm. I was send to L&D; for preterm labor and observation. I was told that if I had them, they wouldn’t survive. I was in bed rest for 3 days at the hospital and thank God everything was stable. My cervix is between 1.6 and 1.9 now, which I have been told it’s ok. Now I’m one day shy of 28 weeks and I’m still measuring 1.8 cm and my cervix is closed, but this time the doctor told me he could feel one of the babies head. He wasn’t worried at all but I’m freaking out, both babies are head down and they do put a lot of pressure because sometimes I can’t walk but then I’m fine. I’m not working anymore and I take it easy at home, but I’m worried, I want my babies to stay there as long as they can, our goal was 36 weeks but now I will be happy with 32 weeks. Has this happen to anybody? Sorry for the long post I just needed to take it out of my chest.