Suppressed presence with 〜た＋つもり

Grammar Explanation: Speaker's conviction with 〜た＋つもり

While changing into her uniform, Rize hid in the closet when she sensed someone unfamiliar nearby. She tried to completely hid her presence, but Cocoa found her.

ココア:: 「完全(かんぜん)に気配(けはい)を殺(ころ)してたつもりなのに」; "I thought I completely suppressed my presence, and yet..."