I agree, Nicole. Most people outside the community don't think of it because their gender IDs do match their sex. So they equate the two. Gender = Sex in their minds, so Transgender = Transsexual.
But, we know better.
This is why I suggest that community members should use a brief description of what they do if they want to explain it to someone, rather than pick one of the half-dozen or so labels we have floating around the forum, which everyone defines differently. But, if the OP wants to use "TG", s/he can, although the term by itself won't be enough to describe the OP specifically.