Hello, In character creation for my group's campaign I decided to play a Catfolk bard (yes, the Pathfinder Bard) with the Icon theme, but I ended up rolling a 16 that I put into my CHA, and after the +2 racial bonus I hit the max of 18, meaning I can't apply my theme bonus to that score. What can I do for this? Could I still select the theme but not add the point until i get to 5th level for the ability score increase or do I have to choose another theme/go themeless?
You don't have to go themeless/different theme, those extra points are just lost. The actually rules are in the optional stat generation method section.
"You still can’t have any single ability score higher than 18. If points from a race or theme would push you over that amount, you still just get the 18, and those additional points are lost; they can’t be assigned anywhere else."
You can probably work something out with your GM. But if you wanted the book written answer there it is.