Questions and conflicts about lucid dreaming

Ok so I lucid dream probably 1-3 times a month. Generally I could do whatever I want and manifest it too. But as of lately I am having trouble with manifesting my wants. I know this sounds weird but last night in my dream I was talking to someone and I wanted to grow 50 ft, but instead when I attempted to do it, the person I was talking to grew instead. I also wanted to shoot fireballs at him, I attempted and nothing happened. Yet at the same time I had complete control over my actions and thought processes. I understand it requires alot of concentration to do this but I've never had that problem before. I've also realized that if I go to bed around 12 or 1 and can't sleep I toss and turn till 5 and then my brain mentally shuts down from exhaustion. This is where I have lucid dreams the most in this scenario. Is there any explanation as to why? Also I remember hearing that if you speed up your breathing right before you sleep or if you wake up and do it you have a higher chance to lucid dream is this true or relevant in any way?