How can I be a better daughter? D;?

So my parents have just split up, they both have partners now and everything. And my mum is having to raise me and my little brother (who is 5) by herself, basically. My dad isn't a very nice man. Well he is when he wants to be, I don't like him that much though. My little brother is quite misbehaved, he sometimes doesn't do as he is told, he hits me and sometimes hits my mum (I know, a 5 year old.. its crazy). My mum is a very good mother, I don't want to make it sound like shes a bad mum because she isn't. She's just too soft, a bit of a push over really. I've never really been an angel either, I do behave but its just I never do as I'm told, I never get up in time for school so I'm usually late (and I only live literally 3 minutes away D:) and I don't do jobs around the house either. And I know only I can do something about it, I feel terrible and guilty and I feel sorry for my mum because she's sooo lovely and she'd do anything for me and my little brother and my other siblings, I try to be as good as I can its just me and my mum get on each other's nerves sometimes and I just shout at her when she annoys me, and I feel awful. I know you're probs thinking ''Well why don't you actually behave'' but it's not as easy as it sounds, getting up in a morning is a real struggle for me haha, and I try to do as I'm told.. I just don't try hard enough I guess. Could someone give me advice on easier ways to get up earlier and do as I'm told and do more chores? I'd highly appreciate it, I just want to be a better daughter because my mums a single parent and me and my brother misbehaving doesn't help. Thanks :) xx