Heteroromantic and aromantic asexuality are NOT LGBT, but every other type of asexuality IS LGBT. Because being heteroromantic is basically the same as being straight, just without a sex drive. At least, that's how I view it.
i can say from my experience as an asexual woman, i have had no desire to go have sex, it's not a priority and it never will be. when i like someone, i don't think, "oh he'd be fun to have sex with", i like the person for their personality