Low hcg beta levels in ER, no yolk sac

Hi! I took two tests three weeks ago- both were positive. I’ve had symptoms daily since then. Last night I went to ER because cramping was different and didn’t subside, along with blood (not enough to fill a pad but bright red). My estimate was I was around 7-8 weeks. Vaginal ultrasound didn’t show anything “but two spots they weren’t sure what they were” and levels were only 255, as if I was in early pregnancy like a few weeks. I just don’t understand how I could have had positive test 3 weeks ago but levels only show I’m 4 weeks. The hospital I went to wasn’t an OB hospital and I have to go tomorrow to see if levels were doubled. I’m hoping they just don’t know what they are talking about but I feel like they just don’t want to tell me I’m losing my baby or it’s an ectopic pregnancy or something. My first OB appt was supposed to be later this week, we have been so excited, now I am just stressed and broken hearted. If the levels double then does that mean the baby is ok?