have all 12 party members and i rented and visited the Amaranthe beach but i can't find lily but i chat with her in pumumu before .did i miss something or i did something wrong so lily couldn't apper ??
There is no option where you could mess up and miss her.
After the chat at Pumumu, she is in the bottom left corner at the sleeping chambers in your castle. After some dialogs with her there, it's necessary that you unlocked the tactical battle system on the overview map before you can advance.
You get a quest inside the barracks where you found Mirel after you repaired it on the overview map. This quest to find the vanguard squad leaders will unlock the battle system.