Feeling Overwhelmed with Family Responsibilities

I need some positive affirmation/encouragement... I'm babysitting my little brother who's 6, and my other two brothers who are 15 and 17. It wasn't planned for my parents to be out of town, but they have been gone for 2 ½ days now and won't be back until at least tomorrow night... I feel like I'm failing, never gonna be able to do enough. but the thing is, my mom's family has been helping out a lot, I don't even really have to do that much. but I feel responsible for all of them and making sure everything goes smoothly so my parents don't have to worry.