Do I ever like your vase!
Perfect for a few fake/artificial flowers!
(Either cloth - or knitted.)
When I first read that you had completed it by the second period, I wondered how you managed to felt it in class.
I could see you sitting with a bucket of hot water on one side of your desk and a bucket of cold water on the other side, sloshing the knitting up and down - all the while paying strict attention to your teacher.

LOL
Then a lightbulb went on. I bet you felted it at home! DUH.
Instead of altering your stitch pattern (IF that is how you are going to fix the wonkiness), why not put a plastic tube inside the pre-felted knitting - the size you really want the middle to be - and then felt away.
That way, to you could perhaps felt the puckers out of the bottom by "over-felting" it.
Just a suggestion - and perhaps not a solution.
I would like to see your pattern.
I have several part balls of wool - several dozen in fact - that I didn't know what to do with.
Thanks for showing this.