The negative test on the 17th makes me think it was the November 5th
The ultrasound on 22 Dec dating you at 8+5 indicates your last period was on 22 Oct. You would have ovulated and conceived around 2 weeks after that which is actually 5 Nov. So it’s the November one. The October one is probably before your last period so you can’t have got pregnant off that one. That’s all assuming the scan has dated your pregnancy correctly!
I conceived on the 5th of November and was due on the 28th of July... If that helps at all, last period was 18th of Oct
Depends when was your last period? I think though it's the November date