Uh, what do you mean by "failed"? Because that could be interpreted either way--you failed to score AS, or you failed to score NT.
Multiple tests pointing one way should be a decent indication that this could be the correct direction. But they are online tests. False positives and false negatives are common. Like any screening test, they are not very accurate; they only point out cases that should be subjected to further analysis.
How to decide if you need a diagnosis:
1. Do you have significant problems in your daily life that most other people don't seem to have?
2. Are these problems caused by your own lack of skill in some area, as opposed to unlucky circumstances? (If it's circumstances, that'd be the province of a social worker, not a psychologist.)
3. Do you need help to solve these problems? I.e., have you tried on your own and been unable to solve them?
If you answer yes to these, then you should go find yourself a psychologist or neuropsych. It doesn't matter what you actually have, because whatever it is, it would require assistance.
If, on the other hand, you are answering "no" to any one of these questions, then the question of whether you have AS is basically a question of, "Do I have a borderline or sub-clinical version of AS?" Because, if you do not need help and do not have significant problems, then either your environment is absolutely perfect for you, or else you don't have a diagnosable condition. In the first case, self-diagnosis makes sense; in the second case, the best you can do is say "I have autistic traits" and leave it at that.