Measuring big!

So today I went in for a check up I’m currently 39 weeks when she measured my belly it was marking 41 weeks has anyone else had this happen? I’ve only gained 10 lbs from my pre pregnancy weight and at my last ultrasound she was measuring a week bigger but I was 32 weeks at the time. I’m scared I might be having a big baby lol my first born only weight 7lbs even. Have any of you moms been through this and if so how big did your baby come out to be?? I’m scheduled for an ultrasound next Monday but I’m not to sure I’ll make it till then 😬