I'm in the same boat. My therapist says I have it, and getting a diagnosis is just a formality at this point. He's the one who would diagnose me, but I just haven't. My reasoning is twofold:

1) At my age (late 20s), it won't do much for me. Just knowing I have it means I can be aware of my shortcomings and issues, but having the diagnosis itself wouldn't really get me anything.

2) The testing costs money and time.

Given those two, I choose to focus on the day-to-day issues that Asperger's causes me and approach life from that perspective. Getting an official piece of paper might protect me form getting fired if I do something in appropriate at work, but I'm high functioning enough that I don't think it's an issue. I've had one or two moments in a professional environment, but none that cause serious issues.

That said, I don't mean to discourage the diagnosis. Just ask "what will this get me?" Maybe just peace of mind, and that has value. I may get the official diagnosis at some point, but both my therapist and I seem to agree that taking a practical approach to my issues, official diagnosis or not, is a good idea.