Concerned about HCG levels

Hi there,
I had a blood test last weekend and was told that my HCG level was only 47 and was told to come back in a week. Throughout the week, have done some more HPT's and the lines are getting a little darker.

Went back to the doc today who gave me another referral for a blood test which I wont be able to have until Monday. She said if the levels aren't rising enough, they will call me back into the docs, but she didn't say what could happen and I was too scared to ask.

Has anyone had similar experience to this? If so, what happens if the levels not rising enough?

There is an article in the first trimester general discussion section about suggested hcg levels. I dont know a great deal about them but I know they can vary a lot. The reading of 47 might just mean you are only very very early on in your pregnancy. How pregnant do you think you are?
Good luck with your blood test. Let us know how you go. I hope everything is fine.