When should you see a doctor?
If you think you might be pregnant, see a doctor as soon as possible. If you are pregnant, this is an important time to learn as much as you can about your options. If you are thinking about having an abortion, it's best not to wait. The earlier you are in your pregnancy, the more options you are likely to have. Also, the risk of problems will be lower.
Your doctor will ask about your medical history and will do a physical exam. You will have lab tests to make sure that you are pregnant. You may also have an ultrasound.
Source: http://www.webmd.com