Agree…padding an application will be percieved as just that so don’t do it. Focus your application on what you have accomplished, not what you feel is missing.
Keep in mind thay highly selective colleges have extremely low admissions rates - often in the single digits. There is not enough space for all the well qualified applicants. Do the research and come up with a well balanced application list with safety, match, and reach schools that appear affordable and that you would be excited to attend.
And FWIW I would not include a middle school award (unless it is a HUGE national or international level award).