つもり / つもりだ

つもり is a noun meaning "intention". After the dictionary form of a verb, with です or だ, it says what you intend or plan to do; after the ない-form, what you have decided not to do.

Put it in the past, つもりでした, and the plan usually fell through.

ないつもり or つもりはない

〜ないつもりだ is a decision not to do something. つもりはない denies having any such intention at all: "I have no intention of…". It is much stronger and can sound like a refusal.

つもり, 予定 or 〜たい

きごう〜たい is a wish. つもり is a decision already made, so it is firmer. よてい予定 is a fixed plan or schedule, often set by someone else.

Asking about someone's plans

In a question, つもり asks what the other person has decided. Among friends that is fine; to a teacher or a boss it can sound like a challenge, so ask with ごよてい予定 instead.

About someone else, つもりだ is fine when you know their decision. When you heard it from them, つもりらしい or つもりだそうだ says so.

"I thought I had"

After a た-form or a ている-form, つもり is not a plan but a belief about yourself: you think you have done something, or are in some state. The sentence usually goes on to show you were wrong.

The verb form decides the meaning: せつめい説明するつもり is a plan to explain, せつめいし説明したつもり the belief that you did.

"As if" with つもりで

A noun with の and つもりで means acting as if something were so, or meaning something as it.