Verbally insisting that she choose between pursuing something romantic with you or remain just as a friend was a colossal mistake. The game is suppose to be fun, and you have just introduced a significant amount of stress into it. The fact that you even went so far as to put a time restriction on her response is just astonishing.

Nobody wants to feel like they're being sold something. You were pushy and she's likely feeling defensive and apprehensive.

Perhaps the most important aspect to a PUA's game, is his ability to create sexual chemistry that "just happened." If you want to salvage this (which is risky anyway since you work together) then proceed as follows.

Drop it. From here on out, do not mention the ultimatum that you have given her. Out of sight, out of mind. Continue to be the fun intriguing guy that you were when you were hanging out with her and act like your awkwardness never happened in the first place.

As PUAs we never push women, only lead.