You`re right I just need somebody to destroy my theory that`s all
In Deling City Ultimecia only say SORCERESS (HERSELF) NOT SORCERESSES

But I still believe that future generation doesnt know about Ultimecia.Only few people knew about it in the future, but they keep it as secret.

I think the reason why she compress time is not to deny her fate.
She must have another reason.

"Latest Diary Entry (Public)

Finally, we arrived at Ultimecia’s castle. Inside, there were a lot of traps
waiting for us! Our futures were hinged in the balance -- could we do this?

...you know, I just thought of something right now. What was Ultimecia
thinking? She was trying to survive in the only way she knew how, I think. Was she trying to reach all the way out to the past to compress time, so that she could try to erase the fate she knew was in store for her...? Thinking about it that way, maybe what I’m writing is one-sided.

Okay, moving on! If any of you want to ask me in person, I’ll always be around! Think of it as a treat from your local, friendly Garden Festival Committee Director!

Doesnt sound like Selphie to me.