thats unusual to be diagnosed without any procedures, my healthcare service wanted me to have another prem before doing any research as they said my ealry births were probably due to infection or 'one of those things' i had to kick and scream to get answers.
It is good that you are being seen weekly, i was left for 6 weeks with nothing after i had my stitch op, if they do spot funneling then a rescue stitch can be placed before your cervix opens too far, another friend of mine had a rescue stitch and although she is more uncomfortable than me, she is the same gestation as me now.
Even if you have the stitch you will be scared, i thought i would have a stress free pregnancy after mine, but this hasnt been the case, i am now further than i have ever been in my pregnancy and am still worried sick.
Good luck, please feel free to ask any questions you may have regarding the stitch.