J Jones said:
That's what I find ridiculous, as they say it's the same condition although has many different symptoms. That's like saying any virus which causes a running nose is the same virus.
I think it's more like how when you have a runny nose caused by a virus, you are usually said to have a "cold" or "cold virus". Nobody claims that "cold" or "cold virus" always means a single specific virus or even that all colds have the exact same collection of symptoms and severity of symptoms.
All colds must have at least some of a certain set of specific symptoms and meet certain criteria (e.g. be caused by a virus) to be considered colds, just like with autism. Some colds are severe, some are not. Some colds have all possible symptoms, some have only one or two. All are considered "colds".
J Jones said:
Being given information on low functioning autism which isn't anything like me just makes it all more depressing, as it's difficult to find anything I can relate to.
Are you looking for information on the internet or in library catalogues? If so, you could try using only boolean searches -- search for only specific phrases like "Asperger's" and exclude phrases like "low functioning autism" or "severe autism".
If you do that, you might find less information about autistic people and autistic symptoms you can't relate to; However, you would likely also miss out on a lot of good information that you could relate to. (Not only because, as others have pointed out, people can be both "high functioning" and "low functioning" at the same time in different areas; But also because books, articles and blogs about prototypical/stereotypical Asperger's often talk about, or at least mention, all different kinds of autism.)
Personally, I wonder if the level of similarity you are seeking might be slightly unrealistic. If you are hoping for similarities in a sort of "total package" (like all your difficulties and abilities and quirks and whatever else have to match up, absolutely no exceptions for anything you would consider a "low functioning" behavior or difficulty, whether past or present) you're going to be disappointed a lot even when it comes to meeting other people who share the specific diagnosis of Asperger's.