www.genomind.com offers a saliva spit test that will test for your likely response to SSRIS. At least, it did in the past.
Also, after battling this for years for my son, trying just about everything that was offered, I can say that the very best response was from a clinical study at UCLA that, of all things, is a 4-week attention retraining program. The hypothesis is that OCD is at least partly based on paying too much attention to your triggers.
The UCLA program is/was based on research in San Diego (http://nas.psy.sdsu.edu/index.php) by Dr. Najmi that showed this was an effective protocol for adults, and UCLA wanted to study it in kids. Totally noninvasive -- you make a list of trigger words and then you do a computer task (sort of game-like, but not really) that actually trains your brain to pay less attention to the triggers. I saw a huge decrease in symptoms a couple of weeks after he finished the program. It can be done at home with a computer and the proper setup. (The UCLA program requires weekly visits, but they said they might be changing that).
The CUTA people used to offer this program for sale/rent where you could use their technique in your own home. I can't find that reference any more, but if you called them (USA: 619-229-3740) they might be able to tell you more.
Wishing you the best.