Possible Preganacy

I may be pregnant. Actually it's likely that I am. I'm working on my tenth day of tardiness, but have yet to get a positive test. I'm trying to get an appointment for a clinic next Friday (2 weeks from when they told me to come back if my period hadn't started). I know everyone is different, but I'm kind of concerned that something is wrong with me. My mom had a lot of trouble conceiving, and I'm just kind of worried this is that. I want to be excited but I cannot believe that I'm pregnant until a see the second pink line. How long was it before you got a positive result? What could this mean if I'm not pregnant?