From what I can tell by reading, you get tingly and numb.

What's happening to me each time I try is that the tip of my foot, or occasionally, the entirety of one of my hands, will get tingly. It'll seemingly spread, and just stop. I'll start to feel unnaturally warm, even though I'm not even under the blankets. However, I know I can move. I tested it once, when my parents came home at 2 in the morning while I was trying it. I could move, it just took a second to convince myself that I wanted to move.

Was I in SP and I just have it lightly, was I close, or was I just in the starting phase?

Also, if that was SP, what do I do from there? I get these pretty swirls of green light, but no imagery or anything (I'm actually glad!) and I'm not sure how to get into an LD from there.