Thought I was 10 weeks but nothing shown on ultrasound

So it was confirmed I was pregnant a few weeks ago and doctors went by my last period so I was 5 weeks. I am now 10 weeks and I went for a private ultrasound last night and there was nothing there.... no sac or anything.

I was told that I'm either earlier then what I've been told or I've had a miscarriage..

Now I'm freaking out because my breasts aren't as sore as they were and I don't feel as sick as I was last week. I called a hospital and they said I have to see my doctor which will be tomorrow because it's late now I'm freaking out!

I had spotting the other day but nothing painful and was very very small.

I also remembered the day me and partner had unprotected sex which was 20th August. Going by that and not my last period I'm about 5-6 weeks.

Do you think I'm just early that's why external ultrasound didn't work?

Or there's a chance I had a miscarriage without knowing?