Whats up

I basically just stumbled on this site by accident the other night and began reading about LDs. It looks really fascinating and I am desperate to have an LD of my own :p

For as long as I can remember, I have been able to tell I am dreaming about 50% of the time, so I guess this is technically a lucid dream, but I really want some level of control. I can already recall about three or four dreams per night, so I'm hoping I'm almost ready to have a fully-fledged LD.

Being the impatient type that I am, I just had to try it that night. I tried to follow the basics of inducing an LD by going to bed, closing my eyes, and imagining having full control of my dreams... and it just about worked!

For about 15 minutes or so, I had a dream about sword-fighting where I actually had limited control (whether or not I was totally asleep I am unsure of, but my mind was generating scenery without prompting), but then my head suddenly jerked and I awoke with a start. I was far to terrified to try again and just went to sleep as normal.

Yesterday, I was back on this website reading stories about LDs and different methods for inducing them. Of course, reading the articles convinced me to try again, and I attempted the same method as the previous night. This time I saw the scenery of a battlefield, and I was lying in a trench (I was still conscious at this stage). I went along with it for a while, and then I noticed that it felt like my room was spinning and my dream began to go very dark. I also found that I couldn't move my fingers very freely and panicked. I quickly sat up in my bed and ran a reality check to make sure I truly was awake. I was, but too afraid to conduct any more experiments.

So does anyone know what this jerking and loss of movement is? My first guess was sleep paralysis, but I wasn't asleep, so I assumed it couldn't be. I was also wondering what it is like in a lucid dream - can you leave any time you want?

Thanks in advance.