My cervix is also "nearly flush with vaginal wall" - it's not a diagnosis that fills you full of confidence for sure!
It's worth bearing in mind that some short cervixes are actually fine in pregnancy - it's whether the cervix shortens that is the issue, not how short it is to start with, if you see what I mean. They stitched me because it went from 2cm to 1cm, if it hadn't, I might not have had the stitch.
Having had problems that resulted in the loss of my baby with my first stitch I was keen to only have one if necessary this time. At the end of my last pregnancy, they weren't sure whether my cervix would be OK without a stitch as it was infection that caused the loss.
Unfortunately there are risks with a stitch and it is important to have a balanced view that whatever treatment option can sometimes, as I know only too well, mean problems for the pregnancy. I can understand that going for a stitch might seem like the safe option but actually studies and figures show that it may not be. You must make the choice that feels right to you but please do make the choice with full knowledge of all the factors involved.
If you are just monitored, try and insist on weekly TVUs from 16 weeks to at least 24. That will catch any shortening. You will be fine for a stitch in this period.
What actually shortens the cervix is contractions of the uterus and pressure from the growing baby. This is why progesterone is so effective as it keeps the uterus calm. My cervix probably shortened due to the amount of sex I'd had in the previous week (orgasm causing uterine contractions) - whoops!
Once you are 26 weeks or so, the pressure on the cervix from the baby is considerably reduced which means the problems from IC are less likely to rear their ugly heads.
One other point - if you're not comfortable with the approach your doctor is taking, make a fuss until you are given what you want.
Below are a few links you may find interesting:
apps.who.int/rhl/pregnancy_childbirth/complications/preterm_birth/vqhcom/en/i ndex.html
www.iame.com/learning/cervlength/cervlength.html
www.healthline.com/bl ogs/pregnancy_childbirth/2008/08/cervical-incompetence-and-cerclage-3.html