I have literally not seen her in any of my matches for 3 months, except when I play her. What is wrong with her?

Edit: After reading some posts here I think I have some ideas for buffs.

Her Q: I like it, I think its a nice spell, although very underwhelming if you dont level it.

W: Love the movement speed, but the heal is underwhelming, either lower its mana cost or give it a slight AP ratio buff.

E: Needs to be changed, you need to level it to rank 5 and have 40% CDR for you to have 10 out of 10.8 seconds on it to be active. Make it a toggle, maybe every time you attack with it it costs mana.

R: Underwhelming compared to Trynd's ult, although he can only use it on himself, it lasts for 6 seconds and can be used in any CC, or hell even Morg's Black Shield. I don't know what to put here, but it does need something.

she sucks.

what is right with her?

I haven't a clue, actually.

The game evolved. She didn't.

I just had two in my last game xP

Mana costs are outrages. You are basically live with no mana.
Her ult is a whopping 2 seconds, whereas with others you get 6+ second ults that are similar in nature.
Her healing is worse than Nidalee.
She has to be fed or farm like mad until she has Nashor's and Rageblade.
Her Q does very little damage now.

Add to this: kayle cannot ult if stunned or silenced. Go figure.