I think shes not interested or her mind isnt made up. She using you to give her the boyfriend vibe. So she feel cushioned by her previous brake up. I would personally stop looking at her social media, dont give her any special attention and act like shes a normal coworker.
Get on your grind, focus on your life and if she really wants you she will initiate a date, she already knows that your willing.
When she seeks validation from you in the future dont give it to her, she may try to bait you asking "do you think I'm pretty"? You could say somthing like, I'm not sure.. or I dont see you that way anymore... doing this will spark her interest in you more. She wants the prize not what she has already won.
Start to ramp up your social media, post photos of you at outings, doing fun things, eating meals, just post the food not who you are with that will leave her to wonder etc. This will make her feel like shes missing out, even date a girl and speak to people in the office, tell them it's not serious and your keeping your options open. This will get back to her. This will force her to act, although you know the context, so it's your choice.
The point is, every girl I've met, who liked me made things happen, only teases, which she may be cause you problems like this. You have to work out is she a cock tease or just using you for the boy friend vibe.
If she is a cock tease, you should follow my advise and she will come running. If it's just for validation and boyfriend vibe, well thank god your mind is free of her and concentrate on doing you.
Try to become more of a focal point of conversations at work, for example start the gym and look amazing this will get people talking about you. Or do some amazing achievement like climb a mountain or bungee jump, get a qualification etc...
Leave reminders of yourself in the office, maybe put a photo up somewhere or item, like a plant, so when she comes in she thinks of you.
Also when she starts to show interest, dont break tension, allow her to sweat it out, the more she thinks of you the more time she invests the more she'll want to be inloved with you.