I agree 100% that psychology is a science. I think the confusion comes because in the past psychologists have often failed to follow the evidence-based rhetoric that's prevailed so strongly in more 'pure' sciences. This being said the field is improving immensely and as 'science' as a concept is being tought more and more to all science students (insteaf of just facts etc.) people are sticking to the rules of science a lot better.
Coming from a background of medicine, this is a problem we face a lot too. How do you split what we've always done because we assume it works, from what actually works!