Possible miscarriage?

I am 6 weeks and started spotting it's brown and light pink went to the ER and they did an ultrasound saw nothing in my tubes no gestational sack . My lining was thickened and they saw hypoechoic focus with fluid in uterus. My hcg was really low at 106 and they sent me home . I'm so sad as I believe I am miscarrying. I am worried it could be ectopic because two weeks ago my hcg was 139 but they did not see it in my tubes. I am so sad all I can do is wait