Why is my cat so clingy. Ive had kitty for 15 years now and bless her heart, she has none of the qualities?

of a cat that i used to hate about them. she is extremely affectionate, wants to be held constantly and licks my face nose hands whatever she can get her tongue around lol. she sleeps on my pillow next to me at night and lays her face on mine purring contently. and best of all she doesnt get up on my kitchen counters, because i hate that. so my question is out of curiousity, why is she so clingy. why does she feel the need to always be held and loved on. i give her my full undivided attention but the more i give her themore she wants. like right now, she's licking my fingers while im trying to type my question. when im on computer she wants to be held close. if i read a book she either keeps pawing at the book or at me until i stop and give her more attention. shes always been affectionate but in last 6 months its really getting out of hand. is she trying to tell me something. due to her age i often worry if she knows shes old and wont be around much longer so shes getting love now.