Hey!
I'm similar to the others. The first BT I had was on the day i got my BFP and my level was only 79 (at 3 weeks). My GP said that it was so low because it was just very early in the pregnancy.

She told me if I wanted to do another BT test in a week to see my levels go up then that was okay with her. So I went back exactly a week later (4 weeks) and my level was now 1400. I'm 5 weeks tomorrow.

I dont think I will have another BT between now and my 8 week scan, now that I've had the reassurance that they were going up. If you just want the reassurance I'd ask for GP for another one and then if you wanted to ask for the early dating scan.

But Congrats on your BFP! Its very easy to worry (I'm doing it constently too! lol) but just talk to ur GP if ur unsure