Beta was + but VERY Low

So I had my beta today. I totally did not want to go. I was already spotting and "knew" AF would be here soon. So I went in got my blood drawn and snickered "what a waste of time". As the day passed I had this nagging feeling that my beta would come back positive and be a chemical pregnancy. Call it woman's intuition. But I just knew. As I thought my beta was positive. But, very low. Only 12. Should be 25+. Progesterone was 13.5.  RE said it's still early and can go up. And that spotting is normal in the 1st trimester. I was numb. I'm pregnant, but will probably miscarry. I am trying to remain positive but I am trying to be realistic. Please keep us in your prayers. Our next Beta is Monday morning.