Dates could be wrong, definitely.
I was measuring 7 weeks when I was 8 weeks at one point and then the next time, bubs was measuring as I originally thought.
Unfortunately, the only thing to do is to carry on as normal, try to relax and stay calm and keep your fingers crossed for your little one. You still have a good chance that all is ok.
One thing I have learned is that we must have faith in our babies. I was so anxious in the first part of my pregnancy and can be still now, but each time, my baby has shown me that it is stronger than my mind.
I had a miscarriage and tried to have faith in my baby, but learnt that I didn't do anything wrong and my baby just wasn't meant for this world.
It's such a time of feeling like you're in limbo between those first scans, but keep your fingers crossed (again!) and trust in your little bean.
Hugs - it's ann annoying time, but whatever happens you will get through. Xx