Shortened cervix?

Megan
I went in today to have my cervix checked at 26w3d. I went from 3cm two weeks ago to about 2.4-2.2 when pushed. The doctor is concerned but didn't put me on bedrest yet. He recommends 'reduced activity' and laying as much as possible. I'm cutting down my hours at work - where I sit a majority of the time - to half days (about 4 hours at a time), but I'm worried I'm not doing enough.
Has anyone had this and carried to at least 32 weeks? I'm getting so nervous.