Cervix length

Mamas yesterday at my appointment I was told my cervix length was only 2.1 cm and a month ago it was 3.5 cm AND my placenta moved on top of my cervix so I have full placenta previa. I was referred to a high risk doctor and put on bedrest but feel clueless. Does anyone have any experience with this? I’m tired of googling and getting myself upset 😕