You have just illustrated my point. You do not have to label everything you do, but you do have to use labels like "underdressing", "male", "straight" and "crosssdresser" in order to communicate effectively about those things, as you just did. No one is forcing you to communicate effectively, just as no one should suggest you are anything more or less than what a given label defines, but it is absurd for anyone to suggest that the term crossdressing does not apply to the act of donning clothes typically associated with the gender opposite of that with which one identifies.