Short answer... NO! You can't be gay for your attraction to transgendered women. 4 simple facts, and notes...

Fact: Gay men like penises
Please note: A particular amount of trans women will have negative emotions towards their male in-betweens.

Fact: Gay men often like hard/muscly/hairy bodies.
Please note: Transgendered women often have soft, curvy bodies because of the hormone reassigment therapy, and how it induces the female hormone, estrogen.

Fact: Gay men like men who identify as men, live completely as men, aside from the possible weekend drag gig, or similar, or alike.
Please note: Transgendered women have breasts, and gay men, while some are admirers of them, are not "into" boobs like straight men are.

Fact: Gay men are worshipers of the male form, and are not secretly straight. A true gay male is terrified by the sight of the female anatomy, and is not likely to engae a female sexually.
Please note: Trans women embody the feminine form, and do not resemble men, as we accept men.