Maybe you need some friendly competition to motivate you. Here are some competitions that might be interesting to you. If you are seriously considering entering the competition talk to one of the adults and of course your parents.
Also, look around your community and see if there are problems you can solve using your engineering skills. Does a shelter need beds for their dogs or a way to automate feeding of animals? Does a retirement home need an easier way for senior citizens to get in and out of their facility? What about games for disabled children?
Future City - Offers a fun way for students in grades 6-8 to learn about cities of the future
Science Olympiad - Science Olympiad functions much like a football or soccer team, requiring preparation, commitment, coaching and practice throughout the year. Each school-based team is allowed to bring 15 students who cross-train for a variety of events in their skill set, but some school clubs have more than 75 members, allowing for an apprentice and mentoring system.
Technovation - Every year, Technovation invites teams of girls from all over the world to learn and apply the skills needed to solve real-world problems through technology.
Hackathon!! - Every year Techpoint Youth hosts a hackathon in Indianapolis. There is also a hackathon at IUPUI around November. If you're interested we'll get more details.
TEAMS - Tests of Engineering Aptitude, Mathematics, and Science (TEAMS) is an annual competition for middle and high school students designed to help them discover their potential for engineering.
National Science Bowl - Sponsored by Department of Energy, the National Science Bowl challenges middle and high school students to face off in a Jeopardy style science contest.