Confused about measurements, possible due date change

So, my due date has been August 10th since my first appointment. I've had several ultrasounds this pregnancy only because my little girl hasn't cooperated and it took three different appointments to get all of the measurements. My uterus has been measuring "much farther ahead" for my midwife, enough for her to want it looked at in ultrasound, and the baby has been consistently measuring ahead on ultrasound. However, I don't see my midwife until Tuesday so I haven't been able to hear what she thinks yet. I got an email today with the dictation from my last ultrasound and they have baby measuring at 30 weeks when I was only 28 at the time. Has anyone had such a large difference in dates and then had a change in due dates this far along? Or, at this point would it just be a normal enough difference? I will of course figure it out with my midwife on Tuesday but I'm confused and anxious to know if this puts me further along? By the way, I don't have GD.