Low blood level ...

Has anyone have a low blood level to start with then continued normally? By my last period I should be 5w3d today but since I have two occasions of bleeding, I don't know for sure. Went to ER last night did urine test + and blood Quant test + with 68. Going back on Monday to do another bloods. According to the level I'm more like 3-4weeks. (ok had sex on oct 11 12 13 with a + opk on the 12th, only time I had sex that month)