Help please

Cindi

I got my first positive home test back on 10/20. it kept getting darker every day there after. I've never had a normal period so trying to use that as a tracking tool is no help. I went to the ER last night with slight pain in my abdomen . my hcg level came back extreme low, dr. said I may be like insanely newly pregnant. but if I started getting BFP test back on 10/20. Why would my hcg level still be super low? anythoughts?