5 weeks 2 days. No yolk sac

Thought I was 6 weeks + 6 days based upon LMP. Ended up going to the doctor earlier to rule out an ectopic pregnancy as I was having brown spotting and left side pain.

Ultrasound only showed a gestational sac. Nothing more.

Whilst with DS I at least saw a gestational sac with yolk at near 5 weeks. (Had an early scan due to brown spotting which progressed into red bleeding )

What am I to think of this?

I have to go back for a repeat ultrasound in 2 weeks