They are testing the HCG level as you know and they look for the numbers to be rising. They typically double every two days in early pregnancy. I believe you are within normal based on this chart:
http://www.medhelp.org/user_photos/show/762924?personal_page_id=3164123
Did they say anything or are you having blood work in a couple of days? While you are on the lower side, that is really meaningless in terms of the pregnancy. The point will be if they rise and I expect they will. Congratulations!