Thanks OnErth and Literati!! Gah, it's so hard not to worry over every little thing. It's so hard to know with measurements too. Baby was curled up in a ball sleeping for most of the scan and they mentioned that it made it difficult to measure so who knows.
Good luck tomorrow OnErth, I'm sure all will be wonderful! I wouldn't worry about 2 days behind, DS was measuring behind by that much at my 7 week scan (and I was absolutely sure about my dates then too) and then at my 12 week scan he was measuring a day ahead.