Puberty or not?

  Please help, I am a 16 year old male and for about 6 months now one of my testicles has been significantly larger than the other, about 4 times bigger.   It is not painful to touch or anything like that just a bit sore running sometimes.  Is there something wrong with me or is this normal for males my age?
  Also I always get erections really easily, even just holding hands with my girlfriend or something like that I feel it twitching in my pants, this is embarrassing because I have to get up and move away from her to try and keep it down.  Is there anything that can help stop this.
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Dear Young,
Testes are usually approximately the same size. Varicoceles, trauma are a few causes for a seeming or actual size difference. You must find out what is causing this disparity in each case. From your description of fairly recent onset I am particularly concerned about a testis cancer. You need to be evaluated by a urologist by early next week at the latest.
As regards your erectile concerns, what is happening is quite normal and something with which  we all learn to adapt.
GO TO YOUR UROLOGIST!
Sincerely,
HFHS M.D.-SAL
*Keyword: Testis size, testis cancer