Awesome dream control for a first lucid. I still haven't managed to summon a DC more than once.

I shout at myself that this is "my f**king dream" but seem to have no luck.
Keep in mind that the best way to keep a dream stable is to remain calm. Any kind of excitement can easily distract you and wake you up or end the dream. Try focusing on your surroundings more, using all five senses, and feeling the things that are in the dream with your hands.