Only you can really say if your attraction to trans women was a fetish or not. It doesn't sound like it is/was - but that's not really my call.
As far as desire waning for trans women - I've heard about that happening before. It's part of liking any particular physical attribute - like hair color or ethnicity, sometimes one goes through periods where some physical stuff is more attractive and periods where it isn't. For example, I have a specific type of guy I'm attracted to on a purely physical level. The problem is, that type changes pretty darn often,
Some months or years I'll love a scruffy dark haired guy, other times I am drooling over read-heads, still other times I have a thing for Latino men. If I genuinely dig someone, though, none of that actually matters (well, usually doesn't matter
).