Assuming this is a serious post, I'd say the shape of your penis sounds fine. Is it thick only in the middle part of the penis, or are you concerned that it is simply too thick all around? If the latter, then be grateful -- thickness or girth is a good thing!
As for the semen issue, it is possible that it is thinner in consistency after a wet dream because there is more fluid in it, and it is the buildup of that fluid pressure that can trigger wet dreams. Alternatively, it may be thicker when you masturbate for the opposite reason: you are taking matters into your own hand (pun intended) and releasing semen before it builds up as much fluid.
Hope this helps...