First pregnancy, no symptoms, kinda worried

Hi my LMP was April 24, no cycle in May, test positive on June 2. First appt was on June 8. Which according to my  LMP made me six weeks. When I got the US done they could only see the gest sac/ yolk sac. Is this normal? I'm not having any symptoms other then cramps maybe twice a day in the mornings when I wake up and around 4 or 5pm. I go back to the dr on June 22. And I hope everything is fine!!!!