The best way to proceed with this girl from the gym is to be more decisive.
You should have asked for her number after she agreed to the coffee date.
By the time you saw her two weeks later, she may have thought that perhaps you had forgotten about the date and thereby she didn’t say anything about it.
You were worried about not coming off as thirsty if you were to start a conversation with her about the date and she was probably worried about the same thing.
She may have wanted you to take the lead on this.
After all, you were the one who asked her out.
Again, you need to be more decisive with her.
Next time that you meet her at the gym, ask her if she would like to meet up with you after her workout for juice or a beverage.
Your gym may actually have either a juice or beverage bar within it or one that is close by.
This move makes you come off as a lot more decisive and self-assured.
Unfortunately, your indecisive behavior so far, may have closed your window of opportunity with her.
However, that is not absolutely certain.
This means that time is of the essence.
Hence, the next time that you meet her at the gym, you need to make a decisive move in making that date happen.