つもりだった

つもりだった means "I was going to": after the dictionary form of a verb, it gives an intention you had, and almost always one that did not work out. The second half, joined by けど, が or のに, says what got in the way.

The past tense does not by itself mean the plan failed. With さいしょ最初からor a similar phrase, it simply reports what you intended at the time.

"I thought I had"

After a た-form or a ている-form, つもりだった is about what you believed you had done or were doing. Reality turned out otherwise.

The tense of the verb is what tells the two meanings apart.

"I meant it as"

After a noun with の, or an adjective, つもりだった says how you meant something, or how you saw yourself – and others took it differently.