The DSM has criteria for all the disorders. To find criteria for the current version of the DSM (DSM IV, text revision), you can google dsm and the disorder you are interested in, or simply "dsm criteria". Lots of sites list the criteria. For example, the www.behavenet.com site is a good one. Here is the link, for example, to the criteria for depression:
http://www.behavenet.com/capsules/di...s/mjrdepep.htm

Be aware, though, that you need a mental health professional to make a diagnosis by meeting with you in person. Your therapist is trained in this--have you asked him/her?