Have a few of these
Then please, for your own sanity and that of those close to you, try to calm down a little and, while its easier said than done, try to not worry so much.
If the MW does not seem overly worried, take it as a positive sign. Start looking for a few more positives and not only the negatives here. If she had said there was something wrong then yes, I can understand you panicking but as she seems quite calm about things and wonders if your dates are maybe not quite right, then its not a bad thing.
If you tested positive on Boxing day, depending on dates (and they can always be wrong you know, even if you are convinced they are right) you may only be 6 or so weeks along even now, so there really might be nothing much to see.
Most women don't have early scans, so if unsure of dates, you have to be prepared to find out you are not as far along as you thought. If you wait 2 more weeks hopefully there will be more to see.
Keep positive. A good friend of mine said her marker (she is a mum to 4) was that she woke up every day and still felt PG. She had sore boobs, morning sickness and a few other things, so took heart in that each time.
But please don't sit and fret for the next two weeks. It won't do you or anyone else any good.