Science tells us the human brain is not fully developed until age 25 and from my experience with myself and those around me I would have to say that, mentally and emotionally, true adulthood doesn't begin till around that age. I can't speak for Germany, but here in America I don't know of any 19-year-olds who truly know who they are or what they want from life. I would say go ahead and begin the search for a willing surgeon so that option will be there when you are ready, but spend the next few years learning as much about yourself as you can. Castration affects your life in ways you never imagine beforehand, and you need to be equipped to deal with the surprises as they come. Therapy is certainly beneficial, regardless of whether you specifically discuss your castration desires with your therapist. The process of self-discovery in itself will bring you much closer to true awareness of what you need. I know six years must seem like an eternity at your age, especially considering how long you've been dealing with this already, but it is far better than a lifetime of regret for a wrong decision. If this is worth doing for you, then it is worth waiting until you are physically, mentally and emotionally equipped to handle the consequences.