Need some reassurance/advice please :/

Hello everyone, I am currently 7weeks 4 days according to the first day of my lmp. I got an ultrasound done today at the local pregnancy clinic and was told I am expecting twins but there were just 2 gestational sacs with no yolk sacs/fetal poles inside. I was also told I need to return next week for follow up ultrasound to see if they are developing properly or if I need to schedule a d&c. I am completely devastated and have read in other forums that sometimes ovulation can have occurred later than expected which causes one to be earlier in pregnancy than they thought? Can this be? And has anybody experienced this?:( also the ultrasound tech mentioned she could have possibly seen something in one of the sacs. Any advice would be greatly appreciated