Measuring 3 weeks ahead

Jasmine • Mommy//Wife
Hey ladies! 
I had my doctors appointment last week in which he told me my uterus is measuring 3 weeks ahead. I'm 29 weeks, so that means I'm measuring at 32. He told me not to worry because there are many reasons for it, and we would do an ultrasound at my next appointment at 31 weeks to check on the health of my little girl.  I was just reaching out to see if any of you ladies had been through this before? I'm a FTM, and can't help to freak out a little bit about what's going on.