5 weeks 3 days Twins?

Since a week from today my HCG started at 670 and as of tuesday was in the 4000s. From a vaginal ultrasound they were able to see 2 yolk sacs! So possibly having twins. All i care about is that if there really are 2 that they grow and be as healthy as possible. My first ultrasound at my drs office isn't until I'm 10 weeks and i seriously cannot wait until then. I might get another ultrasound at 8 weeks with a private office. I'm so terrified of losing them, i already love them so much. Id love to hear everyones thoughts!