I've told this story a thousand times, but I think I realize what happened now.

The first time I beat the game, it was really easy fighting him. BUUUUUUT...my brother shut off the playstation before I saw the ending >:[

So, I load up the file again, AND I CAN'T DO IT! IT'S WAY TOO HARD! It's the same file, but it's soooo much harder than the first time!!!! Why???

The only difference was that when I fought Jenova the first time, I got Meteorain (I think that's what it's called >.>).

It makes a big difference, take it from me XD