How did you know? Any early signs?

We did <a href="">IVF</a> and we had two embryos transferred back. Plus, twins run genetically on my side. As such, there is a real possibility of multiples. My first US is Tuesday but I thought I would ask here... Did you know before your first US that you had twins/multiples? If so, how?
I have been dreaming of twins and triplets and would love to hear from others if there are other signs. Thanks!