If you want to get assessed you have to call around and interview some psychologists/psychiatrists until you find someone who is specifically experienced and knowledgable about autistic spectrum disorders in adults. You can't expect any random shrink is going to be competent to evaluate it. To many will say things like "your IQ is too high," and so forth.
If you're lucky you can arrange something low-cost, maybe through your university if you're a student? Otherwise, costs can get up around $2000, and insurance may exclude it. Some psychs seem to abbreviate their assessments to only an interview, which ought to reduce costs, though.
You should also consider the ramifications of having a psychiatric diagnosis on paper -- insurance companies in some places consider that a pre-existing condition. OTOH, if you need help, such as workplace or school accommodations, then maybe it's worth it.
Despite what some people say, once you're out of high school, psychiatric diagnoses are not considered "cool."