Depression Support Group
Depression is a real and debilitating condition that is often misunderstood by family and friends. Its meaning can range from a prolonged period of sadness to an actual mental illness with specific symptoms. Find and share experiences with others who are going through the same struggles.
Many people view "acts of service" (housekeeping, laundry, babysitting) as expressions of love to others. Watching your siblings is an expression of your love for them. Helping mom with the housekeeping is an expression of your love for her. Having dad's work clothes laundered and ready is a way to let him know that you love him.
Perhaps you can ask your siblings to help out. An 11yo can help dry dishes, sweep, dust. The 3yo can "help" with dusting, etc.
I know these suggestions aren't a cure for depression, but many times an "attitude adjustment" makes all the difference.