Concerned about my cervix measurements. Any advice?

[AbbyLink]

A little over a week ago we had our 18 weeks gender scan. They US tech was a bit concerned about my cervix which to her seemed short. It measured 2.8 and the norm is from 3.0-4.0 she was sure my doc would want to see me each week for a while to be sure all was well. My doc is not concerned at all. She said since there is no funneling she doesnt see a problem. I scheduled another appt to measure again in two days (this Fri) to check it anyway. I'm so scared. A lot of women I read about said there doc was keeping a strict watch on them with these measurements. Does anyone else know what they measured or have any advice? I'm so worried about my little one. I get a aches and pains in that area quite often and it doesn't help my worries