How far along am I??

Okay so in the apps I am using it tells me I’m 8 weeks & a few days but when I called to make an appt with my ob for the first time they scheduled me dec 6 (next week) and said I would be 10 weeks by that date. So I’m honestly really confused. My last period was Oct 3. Someone help. They won’t allow my husband in the doctor with me unfortunately so I wanted for us to go to those places where they also do ultrasounds since he could go there but it’s 9 weeks+. I just don’t wanna go and waste my money cause insurance doesn’t pay for that. I’m confused if I’m 8 or 9 weeks.