So I am 5w6d

Last night I went to the ER for very very light spotting, only went cause I wanted to be sure everything was okay. But it was VERY light. They drew blood and my HCG level is at 3288. They did an ultrasound and these are what the notes say “small gestational sac is present within the endometrial cavity. The sac is too small to correlate with a gestational age. No embryo or yolk sac is present. No adnexal masses. Trace free fluid”. I am going back in 3 days to make sure my HCG level increases. Any one have any similar stories? Also did not hear a heartbeat.