Everyone fits under multiple labels, and not just in terms of sexuality and/or gender. I use different ones under different circumstances depending on the the situation I am in although I don't wholly prescribe to any of them. Like I prefer being refered to as gay, as I personally like that word better but occasionally i will refer to myself as a lesbian because some people only understand my sexuality under that term.
Everyone has their preference to how they identify themselves so surely LGBT just covers a wider spectrum, although even that doesn't include every identity possible but then where do you stop? The acronym would become ridiculous!