Yes, be careful. You can be fairly direct with women in most environments without any consequence, but at work it's a different matter. The inability to be direct means that you have to be subtle, which leaves women a lot of room to play games. Women like to avoid giving a direct answer if they're not interested, because then they can manipulate you.
That's why I think you should have invited her out for a drink, which would take her out of the work environment. If she voluntarily socializes with you outside of the workplace you have more leeway, but even then you have to be careful. When she's alone with you at a bar, then you can make your move and see how she reacts. If she avoids putting herself in that kind of situation, that shows she's not really interested.
To me, everything she's done so far shows disinterest. The flirting just shows that she wants attention, whereas it's action (spending time with you alone outside of work, making things easy for you, getting physically close to you and letting you touch/kiss her etc..) that shows attraction.