according to the book of lost memories, silent hill 2 takes place 2 years before sh3... which puts it 15 years after sh1.
your synopsis is cool, but your timeline is off.
*Edit* Upon further inspection, more of your info is incorrect... I hate to nitpick and Im not going into all of it, but you should definitely try to find some book of lost memories translations. They contradict several of your key facts.