A question on my astral projection attempt?

I went to bed and meditated for around 10 minutes, then layed down flat on my back and thought about something I did during the day, I focused on it as well as I could, and at this point I am completely relaxed. And after about 8 minutes I thought I got to the vibration stage, but it wasn't like what I heard, instead of feeling vibrations, or a tingly feeling, I felt the same type of feeling you get when your overwhelmed with nervousness. That's what I physically felt, and I think it was the vibration stage (was it?). Then I imagined that I was pulling myself up a rope (this is a common method), but I couldn't concentrate very well, but I still did it. After about 4 minutes of no success, I unconsciously fell asleep.

1. Was that the vibration stage I felt?

2. Should I have concentrated harder?

3. Should I have preformed this at a different time, than my bedtime?

4. And should I have focused more on the "rope pulling"?

P.S.: I have unintentionally astral projected and traveled before.

Any answers are appreciated.

Thanks

-Clay