Quant Tests Wrong?

I had my hcg quantitative blood draw 12 days after conception. It came back <2, which is negative. Any chance this is wrong? Does body weight alter these results? I ovulated VERY late in my long cycle. I am currently on day 40 of my cycle and no spotting, period, nothing. Any input? I assume my meds to regulate my cycles just isn't quite working and I'm not pregnant.