some of the responses you've gotten so far are inacurrate. The quantitative HCG levels should double every 2 days in early pregnancy. As you get a little futher along, the levels do not double that way anymore. Typically once the level is over 1000 a sac should be visible via sono. Once a viable sac and fetal pole are seen on the sono, that becomes a more useful tool. HCG levels are typically not followed after that unless there is concern of falling HCG levels to track a miscarriage back to baseline. Typically once sono's start, then what we should find is an accurately measured baby for dates as well as a viable heart beat (typically btw 120-180). If say 2 weeks between a scan has occurred, we want to see that the baby has grown in 2 weeks size and the heart beat remains in normal range. Remember... you are considered 2 weeks pregnant the day of actual conception.
Everyone's pregnancy symptoms are different and every pregnancy is different. Just because you don't have classic pregnancy symptoms (ie morning sickness, etc) doesn't mean you don't have a health pregnancy.
You should report any bleeding, cramping. (However these also can be common in early pregnancy). If you have concerns with your pregnancy or display any symptoms of miscarriage (ie. sudden cessation of pregnancy symptoms, bright red blood, or cramping) you should contact your OB immediately. If you are not comfortable with your current OB, you should consider getting another opinion or trying out someone you might find you're more comfortable with/confident. Also be careful what you read (check with your OB if you're not sure of something) and don't go too crazy with the web surfing b/c it usually ends up scaring women more.
hope this helps! congrats! And don't stress too much as this can have a negative impact on pregnancy.