Sometimes if you attempt a WILD, you can end up having a DILD because you've been trying to stay aware. My guess is that your awareness goes away and you fall asleep, but then at some point there's a "hiccup" where you'll regain that awareness, resulting in a DILD.

The twitching is relatively common; it happens to me a lot. It's best to try relaxing as fast as possible, by stretching before lying down, or doing reverse blinking. If you still twitch, try to ignore it. You shouldn't be aware (or trying to be aware) of your body. I tend to look at the back of my eyelids and relax in that way. As for the consciousness, that's the part that you want to be careful with. The objective of a WILD is for your body to fall asleep while you mentally ride the line between consciousness and unconsciousness. It can take some practice, but don't snap yourself out of it - continue to simply observe the scene while maintaining your sense of awareness. This should alleviate the rise and fall in consciousness you're experiencing.