29 weeks with short cervix?!?

Hey ladies. So here's the deal. I went Tuesday for an ultrasound to check cervical length because I am high risk for preterm delivery as I had my daughter at 31 weeks. The tech instantly noticed it was short so she measured and I'm only at 1.8cm and was 3.9 last month. I have been on weekly progesterone injections since 16 weeks. They put me on a monitor and I wasn't contracting at all and also did a fetal fibronectin test and it was negative. I go back on Tuesday to check cervical length again and if it has gotten any shorter they want to give me 2 steroid injections to help mature the baby's lungs faster. And try some medicine to see if they can keep me from going into labor. I'm kind of scared because with my daughter they couldn't stop labor. The medication just drew it out longer and lasted 4 days. It's way too early to deliver and I'm really freaking out. We don't even have anything but a car seat and a few outfits and a platoon with bassinet and swing. That's all. Has anyone experienced this or is currently experiencing this and can give me advice?