If you can get me the X and Z coords of your mining base, and the ends of each direction tunnel wise, I can output a map of it.
Also, mining 2x2 for your branch TUNNELS is best. Once you have a 2x2, just run through and mine above you to expand the Y axis as much as possible. Once that is done and torched up high (not imperative, but looks better, start on the ground under you... a completed branch mine (imho) using the 1 tunnel, 3 solid, 1 tunnel method (which is fastest) should have tunnels that are 2 wide and go from ~20 down to ~6 in the vertical plane. Make sure you start on 16, mine above you to 20 or so (you can still get gold/iron/lapis/coal above 20) and then start mining downward.
Also, if you are doing it right, you shouldn't be too far in any one direction. Your grid should expand around your central point as much as possible, and should expand on X,Y, and Z enough that you won't get too far from your central point anytime soon (your mine should look kind of like a big # with your mining base in the center.
