What do you feel like during twilight stage of anesthesia?

Euphoria: Twilight is an antiquated term. Anesthesia is a spectrum from almost awake to unconscious and paralyzed. I think you are referring to IV sedation. This is anesthesia which you maybe asleep or awake depending on the amount given to you. If you are awake you should expect to feel somewhat euphoric and relaxed.

Amnesia: Short answer. You don't remember because it causes amnesia.

Very Few Know: With modern anesthetics we try and shut down the memory of the patient before they go to the or. Once they can't remember what happened, it is very hard to find out what they felt as they went to sleep. Without sedatives the very medication that is used to put people to sleep blocks memory formation, so we have the same problem. Same with waking up. Patients come to in the pacu after the op.