Help me please

Today I had a little bit of spotting so I went to the er they ran blood work urine and did an ultrasound. My hcg came back as 55 and they said my ultrasound came back with no sign of a yolk sac. Could I just be too early? I'm really depressed right now and very broken up about this. They said to go to my ob on Monday.

P.s. I have read that I may be to early for the yolk sac to appear on an ultrasound, I'm trying to keep my hopes up but it's just not working at the moment. I would really love some good news or someone else's experience.