9 weeks 6 days, good ultrasound but falling hcg levels?

Hello all

I’m after some advice/ reassurance. I’m 9 weeks and 6 days pregnant today and had an appointment with my gp this morning where I discussed my overwhelming anxiety. Because my first midwife appt isn’t for another week and a half she ordered a blood test and also sent me for an ultrasound just to help ease my anxiety.

My ultrasound showed bub measuring on track and a normal heartbeat however my blood test showed that my hcg levels have dropped. At 8 weeks my levels were 189,000 but today, at almost 10 weeks, they have

dropped to 173,000.

How concerned should I be? Is a miscarriage likely? Do I trust the fact that I saw my baby looking good on the ultrasound and let my anxiety go or should I be preparing myself for a miscarriage?