Just a couple of things I'd suggest to think about.
If you were browsing online and found her, there's a chance someone else at work will do as well.
Depends how big the workplace is of course, but with you saying you've not really spoken to her, it sounds like a pretty big workplace, so possibly a non-trivial chance she'll get discovered by someone else. If she's also on OF or something else that might increase the risk.
I'd also just check you are 100% separate between your personal and professional lives with phone noes, avatars, images, devices, email addresses etc etc. so there's no accidental outing of yourself between the two.