Went for my 6w6d ultrasound.
It may just be too early!
I've had friends tell me that they've seen a beating heart at 6w1d on tv u/s (is that what you had?) and others seen nothing until between 7 and 8 weeks!
The waiting game can be scary, anxiety-provoking, etc.
Hang in there and I'll be keeping you in my thoughts and prayers.