ご質問ありがとうございます。
・What time were we supposed to meet up?
=「何時に会う予定でしたっけ?」
(例文)What time were we supposed to meet up? Was it 5 or 6?
(訳)何時に予定でしたっけ?5時でしたか、それとも6時でしたか?
(例文)What time were we supposed to meet up? I forgot.
(訳)何時に予定でしたっけ?私は忘れました。
お役に立てれば嬉しいです。
Coco