Do babies normally measure small during pregnancy?
one of the many books i have breaks down the age by fetal age/pregnancy age. so for example, a chapter will say something like Week 12, Fetal Age 10 weeks. it sounds like they didn't include the two weeks where you aren't pregnant but are still included in the age of the pregnancy. if the tech isn't worried, i wouldn't be concerned until you get further along.
I would think your conception date maybe off, I doubt it is anything to do with your surgery. The early out ultrasounds are usually used to date the pregnancy--it's the later ones where size can vary a lot. If the tech saw a problem she would have had a doctor come in immediately and follow up so I wouldn't worry.
I am 31 weeks preg right now and according to my last missed period I should be measuring 33 weeks but ever since I found out I was preg at 5 weeks I have measured 2 weeks behind. My dr says some women ovulate late. My baby boy is fine and is measuring at almost 4 pounds right now. Try not to worry. Ask God to turn your worrys into faith