"Militia" simply means "group of armed civilians". Historically there have been city, county, state, private, and national militias.
It does NOT state that the unorganized militia cannot be considered well regulated. It does NOT state that the militia of the United States is the only militia there is or can be and there most certainly have been, and presently are, others.
"A well regulated militia, being necessary to the security of a free state,..."
Free state; not United States.
"...the right of the people to keep and bear arms..."
Not the right of the militia, the state, or of the Nation. The people. The individual people as the term is used throughout the Constitution. If you want it to mean something else you'll have to amend the Constitution. Good luck.
BTW- The SC agrees with me.