Cervical stitches. HELP

Hi everyone. i am pregant with my Rainbow. i had a miscarriage at 19 weeks in 2010 and had my other daughter on Jan 2018. She was born at 24 weeks and passed away a few weeks later. It has been recommended that i have a cervical stitch put in, with this pregancy. I have read online that it should be put in at 12-14 weeks, but i don't have an app untill am 16 weeks that is to just talk about it. How would i go about getting the app brought forward? I am so scared i am going to lose this baby and i want to help prevent losing this one as much as i can.