So how far along am I?

I went to a free preganancy care center in April when I was in between insurances just to get some questions answered and to make sure baby was properly growing where he/she needed to be. They had scheduled me for an ultrasound and when I got it done I was 10w6d, but the sonographer said baby was measuring at 9w1d, but was in the right place and had a 173 heart rate. They called me a couple days later and the doctor they practice under had confirmed what the sonographer had said (9w1d with a due date of 12/2/18). When I got my insurance and went to the OBGYN's office last week, I told the Nurse Practitioner I saw about what the care center had said about the due date and baby's measurement; showed her the ultrasound, she said "this is interesting" and ordered me another ultrasound for next week. I am just really confused at this point... am I 11w1d according to the ultrasound? Or am I closer to 13 weeks like they initially told me?