Well I got diagnosed when I was 17, and I would say it has been a great help.
My ASD doesn't hugely impact many elements of my life, but having a diagnosis has helped me understand why I am how I am. It means that I feel less guilty about being myself, and in school, my diagnosis means that staff understand me more, and give me that bit more leeway in lessons to make sure that my emotional state doesn't deteriorate.
If ASD traits are making you confused upset, or causing problems such as anxiety or depression, I would definitely suggest pursuing a diagnosis. Look on the bright side, it is unlikely to do any harm.
Liz