Going to a professional isn't falling into a self-diagnosis trap, but wanting to be told you have might be.
I ended up not really going to see anyone, though. The one time I did see someone, I happened to not really be that depressed at the time, and so he seemed to think that there wasn't much wrong with me, but I wasn't sure I could trust his opinion since I don't think I could effectively relay how I feel when I am depressed to him. I'm going to try and push myself to actually go see someone again, though. Hopefully I'll be able to explain myself better, or at least see someone frequently enough that eventually my feelings will come out.
You might print out your posting and bring it in.