Don’t feel or worried… at this stage ,a lot of things are still uncertain.. but having shown a sac is already a good sign to begin with! Doctor ask you to go back a few weeks later probably to check if everything is falling in the right place..
I went through the same phase as you, I was scared and worried all the time..even when I was 10 weeks, I was bleeding and I freaked out.. but there is really nothing much can be done at the phase.. just take folic acid and continue to have faith… many other things to worry still.. as of now, just lead your life as per normal and be happy!!!
ema