Inconclusive scan 6w4d

Hi all. Feeling very lost and anxious. Went for an early private scan on sunday at 6weeks 2days. They could see embryo, yolk sac and baby but measuring very small (approx 3.3mm) making estimated dates 5weeks 4days. They couldnt see a heart beat. They told me I could have my dates wrong which is unlikely given tracking ovulation and knowing date of conception. Or the other possibility is missed miscarriage. I've had no pain or bleeding. Was referred through my GP today (Tuesday) to early pregancy unit and they said pretty much the same thing and I have to wait 7 days for a rescan to find out if I'm miscarrying. The wait is absolutely excruciating..I'm a wreck and cant think of anything else. Took us 10 months TTC and I am 38 so acutely aware Im running out of chances. Has anyone else been through this, good or bad outcome, I just need to hear from other people who know how it feels!