Overwhelmed with Caregiving Responsibilities

rant... I'm so overwhelmed. I was left at home to babysit my little brother. He's 6 ½ and has severe adhd and anger issues, plus trauma from his birth mom's life while he was in her womb. I love him and want to help him and be able to give my family a break, but I'm just overwhelmed. I'm also watching our 8 month old puppy (by the way, the two of them don't get along)... I'm just so tired of everything. I want a break, but I never get a long enough one. My older brother is watching my little brother now, and our puppy is in her crate, so I'm hoping to get some journaling and reading done. Or at least block out the world by listening to music. I'm 20 btw... I feel like I should be able to be okay with this, or at least not so overwhelmed.