Hi!
While HCG testing is a good way of looking at how a pregnancy is progressing, it is only useful after a series of tests (at least three). For example, you could have had your test just before a big spurt in growth or something - try to get another test or two to see how things are going.
Try to keep calm (difficult I know!) though and try not to get too caught up with the HCG charts on the internet as they are only rough guides, every woman and pregnancy is different. I know it is easy to worry though - when I was pregnant with Tristan, I had a couple of HCG tests done and I was at the other end of the scale. The numbers seemed to go through the roof (at the very top end of the chart and on one test over the top end) - and I was sure when I ovulated. So I started worrying and googling (avoid at all costs!) and started to worry about molar pregnancies and stuff. Well, I was reassured that everything was ok at an early scan at 6/7 weeks and now Tristan is a lovable six month old baby! I am sure everything will be ok for you as well.
Good luck! I hope everything works out.
xxx