Decreasing length of Cervix

Hey, I’m currently 14W5D pregnant with our first (got our BFP after trying for 2 whole years with PCOS).

I had some spotting around 8W but all the scans were clear and baby’s heart beat has consistently been around 165.

However, I went in for an ultrasound yesterday as I had some light spotting and cramps - my cervix was at 3.9cm at 8W then 3.4cms at 12W and when I went in yesterday it was at 3.1cms. I was on progesterone vaginal suppositories up until week 12 and was asked to stop taking them - now my OBGYN has asked me to restart the suppositories and go in for another scan in 2 weeks. He also said he wouldn’t worry until we get to 2.5cms but now I’m scared about how long it would take to get there.

I am so so anxious and nervous - looking forward to hearing about any similar experiences 🙏🏼