Has anyone experienced anything like this??? I need some help please

So I have been on gonal f and trigger for 2 cycles I got my bfp the day of my missed period

I had my first hcg done 18dpo -77

20dpo - 109

24 dpo -126

I have been brown spotting since Saturday my fertility specialist has said I am going to miscarry and stop my progesterone (which I did 2 days ago)

I’m still not bleeding / miscarrying I would have been 6 weeks Friday ...

Has anyone been through anything like this I’m worried that I haven’t started bleeding yet if my hcg is so low I’m also still getting bfp