Hcg not doubling


Hello! I found out I was pregnant august 24 and confirmed it with a lab draw august 25 my hcg quant was 268. I had it re-drawn 72 h later (Monday) and it's only 470. At most I'm only 2 weeks maybe 3 weeks pregnant. I know this because I had to have a iv lab draw 1.5 w before and it came back negative. Anyone else experience this? Thanks, staying hopeful