Scan shows gestational sac no yolk sac at 6weeks

Hi Im 40 years old and was told im in the risky zone for pregnancy. Now pregnant ard 6 weeks or more. My last live pregnancy was 9 years ago. Went for tansviginal scan twice and only gestational sac seen with no yolk sac. Last scan shows 13mm empty gestational sac. Doc ask me to come back another 2 weeks to rescan. Doc said at my age,miscarraige chances are very high.Anybody been thru this? Im very worried.