6 week ultrasound no embryo

So I had a 6 week ultrasound today. All they saw was a little shadow of what looked like a sqiggle so they ordered bloodwork. The doctor said it isn't normal but it happens. Should I be worried im no longer pregnant? I've had two pregnacy test positive. They also did an external ultrasound not internal could that make a difference? Im really worried im no longer pregnant they gave me folic acid pills and some other meds, but I. Feel so defeated like it's not even worth it if im not pregnant:(