Hey, and to the forums!

The problem you seem to be having is that though you don't think it, your probably tend to get excited when your lucid and you worry and rush to try and maintain it, a good way is to confirm that your lucid and then just sit down, be calm and take in your surroundings and admire the ebauty of your mind, this will keep you focused and calm and hopefully make the dream longer. I've been having the same problem and it is slowly progressing.