The waiting process

I never knew what it really took to find out if you were pregnant or not. I always thought that you would test your HCG levels by (well you know on a stick) and if there were two lines that would be it! Then you would go in for a doctors appointment just to make sure all is well. In my case.... let's just say I feel like a vampire is sucking the blood right out of me. I called for my first doctor's appointment on January 17 and had my blood drawn to make sure that I was pregnant. The next day I called for results and the numbers for my HCG was 329. They said that I was still a bit early in the pregnancy and that I should come in for another blood test. Hmmmm.... ok I thought this was a bit weird but then again getting two numbers is a sure way for verification. So I went in on January 20th to get blood drawn and then called the next day. They said the numbers are where they needed to be at 1036. They wanted me to come in again on January 24th to do the same procedure over again. They said that the numbers doubled and are at 2530 but the Doctor still wants me to go in on the 27th for the same procedure yet again. The only thing that I knew was that it was too early in the pregnancy. No other explanation but that.
From all of the mommy forums and boards that I have joined I found out that I should be atleast 6 weeks and 2 days pregnant. But the latest number places me at about 3 and a half weeks. Could I have severely miss calculated?
I just wish I could get scheduled for my ultrasound to actually know. And hence the waiting process begins....