Rising HcG, but no symptoms

Hi all. I got the results from some blood work earlier in the week. The doctor said my numbers quadrupled and wants to see me next week for an ultrasound to check for twins.  But besides my boobs being a little heavy, I don't have any symptoms and it's making me kind of nervous. Don't get me wrong, I'm thankful to not be very sick, just wondering if anyone else has/had similar experiences. Thanks!