It's... complicated.
Crossdressing has some facets.
Mostly, it comes down to, do you present as a man, or as a tomboy, or a girl that just wears comfy clothing? Another possible facet is, do you get a sexual thrill or pleasure from crossdressing?
Having known you in real life, I would say that just wearing man pants and my shirts doesn't really count as crossdressing par se. But, that isn't the be all, end all of it.
Most likely, no, you aren't a crossdresser. If you were to lower your voice, bind your breasts, and maybe even get a packy, then yes, you'd be a crossdresser. ^_^
