Should I be doing more?

Last year we experienced two miscarriages. One of them being a late miscarriage at 16 weeks with our son. I am now 4 weeks and 4 days pregnant. My doctor doesn’t want me to come in for a dating ultrasound for another three weeks. Is this standard? I know it’s unlikely to see anything on an ultrasound right now but I just feel like I should be doing something to prevent another miscarriage. Blood work? Something! Does anyone have a similar experience? Did your doctor see you right away or did you wait? Maybe I just need something to put my mind at ease.