Hi all, new w/ a question...

I'm 7 wks & 4 days, we think. I am going for an ultrasound on Dec 29 for the first time to check the dates. I can already feel my uterus, it is about an inch above my pubic bone. This is my third pregnancy. I read you shouldnt atart to feel it until 12 wks or so , I never felt it this early before. Could I be farther along than I thought or preggy with twins? Thanks