How do I know?

How do I know that my birth control is actually working? I've been taking it a few days now. I am very well educated on the side effects, and how it works. I take them very religiously, haven't missed a pill and taken them and the exact same time everyday. I know about the side effects, and I know about the vomit/diarrhoea rule. But how do I know its working? Is it guaranteed for every woman? Are there signs that tell me besides not getting my period? Help!