I feel like I'm a bad child?

Okay, well there's two things I need to clear up.
1. I feel like my little sister doesn't get enough attention from the family. I mean, my parents pay attention to her but my grandmother has flown over from the UK and she deliberately is showing her that she likes me more than her. It's really depressing for me to see, because I love my little sister and I'm going to be honest here - I don't show it really well. I'm often in a grumpy mood (hormones ugh) and I feel like I'm quite mean to her a lot of the time. I hate seeing her upset and I've just gone through this phase of realization. I hate to even think about what she's dealing with. Her grandparents neglect her, and she's got the worst, meanest big sister. I also quite often see her coming home from school really upset because she hasn't got any real friends and some boys can be really mean to her. She's only 9 and she's already going through rough times.
2. My dad. He works, literally, All DAY. He gets up at 8AM and goes to bed the next day at around 1 or 2 AM. He works all the time to pay for the mortgage, the bills, our education AND I feel like I'm being really greedy. Which is what is really bothering me. I know so many things that I really want but I feel like if I ask my dad to buy it for me, it'll be really greedy of me. I'd feel guilty. Okay so, he's paid $60 for a year subscription to a website I don't even use ( Which I feel TERRIBLE for), He's paying monthly for Spotify Premium ($10 a month)

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