I'm openly transitioning at work, and within my social circle, so I don't really have the same problem, but I agree with the common sentiment here, withholding information until a relationship progresses to a deeper level is just common sense.
I think your dodge of saying you have a condition is a bit misleading. I would remain silent on the matter unless it is of specific concern. While it is a true statement, it's a lie of omission, because there is a very pertinent piece of data missing, and she may feel like she was lied to when the full truth does come out.
This cat is out of the bag, the only way you can correct the situation is to out yourself, which I'm not convinced is the wisest course of action at this point. I would feel her out some more - perhaps plan a group activity with a lesbian or gay couple involved and see how she reacts?
And, in the future, I would say it's better to remain completely silent on the issue of hormones or conditions until you're ready to have the trans discussion.
It's no one else's business until it's time to get naked.
