This is an interesting question. (I'm working under the assumption that that is, as people have assumed, a "ladyboi".) I think it clarifies somewhat to realize that it's—probably—not honestly a sexuality question (unless your attraction really was based on hidden cues of maleness provoking a latent attraction to other males), but rather an essentially linguistic one, that is, "Is it reasonable for others to call me gay because I am attracted to a male that presents passingly as a woman?"

I think when framed that way, the answer is pretty strongly indicated as "No."

It's a little more complex a consideration if the fact that the attractive woman-passing person has a penis is part of the appeal. But I'd still say "no". Words, including the word "gay", are tools of information exchange. In information theory (as well as common sense), the efficacy of communication is how little surprise you have by an actual situation after it's described to you. If your buddy told you they were gay, and had just scored a super hot date, you'd probably expect somebody that looks like this, not like this.

On the other hand, if this is what turns ones crank, that's something else yet again.