How to start talking to someone I didn't used to but know.

There is a girl at work I want to start talking to, she was there for a good few months, but I only recently noticed her and found attractive. In my mind, she'll think "why is he talking to me now when I've been here all this time, something is off". We only really exchange hellos and awkward looks. I don't want to look like I'm forcing anything, it's almost like I'm outside her social(work?) circle, and now suddenly I'm trying to force this interaction. I'm not really scared of the convo that's not the issue, but I cannot get this thought out of my head to break that initial barrier.