The seed is: 464147175
The coordinates are 53 70 30 to 53 74 33 the "Y" axis is measured by what is displayed for your coordinates when you are standing on top of the block.
I hope that this was helpful.
The build pattern is: (C=cobblestone, O=obsidian)
C O O C
O O
O O
O O
C O O C
I can't provide a world download because I am on pocket edition, but I might be able to give you the seed and exact coordinates of the portal.
One more reason I always keep a world backup!
I had something similar happen recently.
I have the exact same issue on the same platform/device.
However, it is not a problem in a much smaller world: 0.68 MB vs. 108.0 MB (although the latter wasn't a problem until the update)
Please fix soon++ it is practically unplayable.