Your examples make me think the the dream is not yours... like the difference between playing a game of football and watching a game of football. Just use "Am I dreaming?"

yah i agree best answer is i saw a dream last night or other night or 3 days ago.4 days ago.5 days ago 10 years ago :)

Its better to say I saw a dream than I watched

i think what you mean is: I saw a dream? I was dreaming? I had a dream?