Crazy8: Never say never, old saying but true. Shutting doors... not good. But I can see where you are coming from and I think it is definitely a step in the right direction accepting oneself the way one is. So there's a good start, which is the most important thing, the first step.
Not being depressed? I am very pleased to hear that actually. Depression is probably the single most underrated affliction that anybody can suffer from, especially bearing in mind that most depressions have the tendency to turn into a very nasty feedback loop, ie. in the end you only feel good when you feel bad. It really messes around with the chemical balance in your brain, screwing up its inherent reward system and that's not a road you want to go down. I've seen a few friends of mine suffer most horribly from depression.
As for the 'never be truly happy'... again, never say never.
What things couldn't you do with a small penis? You could climb Mt. Everest, you could become President of the United States, the way I see it, you can do anything you like, with the exception of being named the person with the largest penis and get an entry in the Guinness Book of Records but I think that you would probably survive quite well.
Think positive. May I suggest you taking up the 'The Five Tibeten Rites'? It is far more then just a physical exercise regime, it can massively improve your ability to get into a truly positive frame of mind.
Here's a link to Wiki, I haven't read the article, so I won't brag about how great it is, some stuff on Wiki can be a bit dodgy, but do have a look if you like.
Five Tibetan Rites - Wikipedia, the free encyclopedia