I'm sorry but I have one question i haven't had answered yet, although it's a bit hard to explain, so I'll use a hypothetical.
Say, Tom, born as a guy, he is transsexual (went through with an operation to change his sex) although not transgendered, as in he is still attracted to females. Now, say he found a partner, would they be defined as heterosexual (Tom was still technically born as a male) or homosexual (Tom is now a female.)
To answer your question, If Tom became a female but was attracted to females, she would be defined as a homosexual being a woman attracted to women. Additionally it would always be a homosexual relationship.Though her most likely partner would be a lesbian woman, even if a straight woman were to be partnered to Tom she would then be defined as a member of a lesbian relationship although her desired preference qmwas men, she would be partnered with a woman. So although one member is not a lesbian, it would still be defined as a homosexual relationship.
Ps. Having an attraction to men or women does not define you as a transexual or transgendered person. Habits or acts of self proclaimed titleing are what defines you as a trans.