Age shouldn't matter. I'm around the age you had your first lucid dream and I have had 2...but I only started trying a week ago. I haven't had many problems with dream control so far, but I have been having some trouble with flying and controlling some people's actions. You need to have full confidence, if you THINK something might happen wrong, it will because remember, dreams are all your thoughts and when you think it, it'll come true. In the past week as I try, I haven't needed to tell myself I was about to dream. In fact, when I tried that, it wouldn't work. The way I always know I'm in a dream is when I try to fly. It's a thought that rarely comes to me, so when I think it I'd know I'm in a dream. Then I'd try to, and suddenly, the entire dream would become much clearer to me. Also, ask yourself throughout the day "Am I in a dream?" and make it a HABBIT. Make it so your subconscious will ask you and answer you. Once you're in a dream and you ask yourself that, your subconscious will answer "no" . I'm not sure if that works, but it seems fair enough to try. Good luck on your journey to LD'ing.