I typed in my seed and it doesn't look like my world. I then clicked update 1.6 and below and it still didn't look like my world. Also I thought new areas are generated randomly, so how does it even know?
World creation isn't random, it's based on the seed.
So as long as Chunkbase uses the same world generation algorythm as MC it can figure out where everything will generate.
But it has to use the correct algorythm for the version of MC you're running.
You say your world was started in Alpha, have you updated the game? I guess so, otherwise you wouldn't have any jungles if they were added later.
If it's updated to a version with a different algorythm then the world will be a mixture of of the two (or more), areas that were explored in an earlier version (or that are close to explored areas) would have been generated by that version and areas explored in later versions generated by those versions.
So parts of Chunkbase's map should look like your world and parts wouldn't.
You should set Chunkbase for the version you are running now and find a jungle that's outside the area you have explored and that should be where Chunkbase shows it even if the areas you pass on the way don't.
If you are trying to find biomes in newly generated areas you should use the current version (which I assume is 1.7 or later) that you are playing on since any newly generated areas will be generated according to that version.
One issue is knowing if you are in newly generated terrain but if you find any biomes which were added in 1.7 you can be sure that you are in the right area; you can use a mapping utility like Minutor to see how much you've generated (note - it will not show anything that hasn't been generated yet), and I'd suggest using AMIDST since it is easier to use and includes a biome highlighter that lets you highlight jungles.
That said, I used AMIDST to look at your seed and found several jungles within 5000-7000 blocks of spawn; the locations given are for the nearest edge from spawn (which is not the same as spawn in your world but it is generally close to 0,0; which one is closer also depends on where you settled and whether you generated any terrain in that area prior to 1.7):
Jungle #1: -4400, -2850 (to the northwest)
Jungle #2: 1000, 6450 (to the south)
Jungle #3: 6300, 2300 (to the southeast)