Kristy,
It's only been three days. It is too early for the pregnancy test kit to detect a pregnancy. I know that Clearblue needs you to have missed your period for about 2 weeks (someone please correct me if I'm wrong) for an accurate test to be made. In the meantime, and I know this is easier said than done, but try not to keep thinking about it. Otherwise, its non-appearance will make you more stressed out.
Importantly, does your period come irregularly? If not, have you been facing a lot of stress in the workplace recently?
If you're not ready to be pregnant (and if it turns out that you are not this time round), please go consult a GP and discuss which type of birth control will suit your lifestyle best.