ive had similar things happen to me..once i was in a dream, realized i was dreaming but i couldnt function in the dream bc i knew i was laying down with my eyes closed and i struggled forever to open them..ive also had yah the feeling of laying down and i couldnt walk properly

these are only weak lucids, and bc you arent letting your mind truly 'go' into the dream
could be because you arent as experienced in lucids, or your having trouble letting your conciousness join your subconcious counter-part, ie get lucid