Expecting TWINS!!!! 😍😍

Today I went for my first ultrasound and found out that I am 5 weeks and 5 days pregnant with twins..... 😍

One thing which I did not understand is that the doctor said ..."it's just a sac. Two different sacs. Let's not be so sure that you will babies in both the sacs. Let's wait for the heartbeat. Will do an ultrasound after 15 days again"....

What does this mean?

Anybody else in the group went through this ....? Please let me know. I am going crazy out of excitement.