Prioritize
First things first. Perform first of all those tasks that cannot wait, like preparing breakfast each morning by waking up early enough. Clean up the house before washing up for school. Market when school is through. But get as much help as you can from your siblings and even your working parents when they are home and available. Suggest that some tasks be re-apportioned among you.
Do any other extra tasks when the necessary ones are finished or handled by someone else. As you go along, you will find some time to attend to non-priority activities which you have long wanted to do, like sewing, re-arranging the sala and writing or mailing social letters.