I'm 19 and I've never been in a relationship before :(?

I would act laid back around the girl at work, like nothing happened. It gives some girls a ego boost to think a guy is pining after them, so act disinterested and laid back like how you would treat anyone else. I wouldn't worry about not being in a relationship, it tends to happen when you least expect it. I think making new friends is always a good thing as it introduces you to new people.