I understand your reluctance to see a psychiatrist and yet there may not be another good choice visible at the moment. I made that choice at two times earlier in my life. The first time I simply refused any drugs (after a short trial) and we made a lot of progress. The second time I used the drugs to control my symptoms and then stopped taking them when I reached my goal. By the second time, though, "talk" therapy had pretty much been branded as a useless waste of time, and I continued it with a psychologist, not a psychiatrist.
Knowledge protects -- ignorance endangers. The first time around I was deeply suspicious of all drugs and doctors because of my religious beliefs. It turns out that, warped as it was, my church was not that far from wrong about this particular point. By the second time, a number of books had been published exposing what was really going on in that branch of the medical industry, and I was at least aware that things might not be as they seemed. That minimal knowledge may have saved my life.
So go ahead and do what you need to do, but I would suggest that you (not your girlfriend, yet) read Anatomy Of An Epidemic by Robert Whitaker. It contains information that might discourage you from seeking help at all. I think, though, that it is OK to do what you are doing and that it could very well help. Just don't go there without understanding the game and, most importantly, where to find the exit! And remember, longer term, that diet may very well be the key to dealing with the underlying causes.