Welcome to the board.
Your story is very interesting as it tells the story of most typical witness children forced in to baptism over the past few decades.
However you will note that over the past couple of years most elders are trying to put off their children from baptism at a young age simply because of the fact that the odds are stacked against them ie they don't want them disfellowshipped as a minor, however more on that point in a thread I intend to post later.
I think that most will really feel for you on this board because of your experiences with the "truth", and will feel that you have made the right move talking about it on a board such as this, I am sure that you will find the support and help that you need.
As to the question of your baptism being valid... I haven't read your other posts but are you Dfed or Daed?
According to the society rules your baptism is valid, the only thing that can really invalidate it is mental health or the like and even this is very rare.
However that is the society rules, I suggest that you use your own rules in life and decide for yourself whether it was valid or not.
As regards to legal action, this road would not be a wise one as ecclicastical law is very complex and weighs heavily in the favour of the religious body.
Cas
Please feel free to PM anytime