You're probably not using your material wisely. The material you have will stretch a long way granted you know how to keep it sounding interesting. Look at some of Beethovens works, he'll use the same cell often 30 to 40 times without pause. Try going in to some of your pieces and find ways that you can repeat a phrase but make it sound like it is more a continuation then an exact repeat. It's like writing in English class. You have your main statement, but then you have to flesh it out. Everything you write after that statement still somehow pertains to the topic, but in contrast to the topic.
Wow, I don't know if that helped or made you more confused.