When a portal is first created from the overworld to the Nether, there is no guarantee that using the reverse portal will send you back to the original portal. The reason for this is unknown, but is possibly related to placement issues (the Nether portal might have to be moved because it would otherwise be in solid rock/lava/etc.)
It is possible to make the portal you build on 'earth' go both ways with a portal in The Nether. To do so you need to build a new portal in The Nether in a position relative to where the portal you first built is. When you travel to The Nether, and then return, you usually emerge from a different new portal somewhere near your original one. Work out the relative position of the new portal and your original, and remember that travel in hell is around 1 block = 16 in 'earth'. Build a new portal in The Nether at the appropriate location, and your original portal should now link to it both ways
wiki quote for why portals don't link right
this is going to be very hard to figure out my portals aren't even facing the same way so I can't work out where the other one is
It seems that your direction doesn't change when you go through a portal, so one way to do it is
A) create a portal in the real world
B) go through the portal
C) return immediately through portal
D) Break the exit portal
E) travel from the exit point back to your base in the real world
F) enter the first portal facing with your back to the exit portal
G) When you appear in the Nether, you will be facing in the direction that you need to build the new portal.
H) Move 1/16 of the distance in that direction and create a new portal. Break the old portal.
I) Go through the portal and hopefully you end up at your base portal.
J) If not, return to D and you should get nearer with each step.
Poll