Same here. I'm 19 and have 3 siblings, 14(f), 12(m) and 4(f). The 4 year old doesn't get on my nerves (because she's 4, obviously), it's just the 14 and 12 year old. Especially the 12 year old.
With those two, there's no emotional support, no affection, no love. The 14yo and I can get along well, but wanting to keep the way things are, I try my best not to play with her too much, because we are just now starting to get along. Doesn't want any hugs nor kisses from me, so I don't want to break our bond by irritating her and making her uncomfortable.
As for the 12yo, I am surprised he's not even dead yet (literally). He gets on everyone's nerves and you can't tell him shit. He's not even mature enough for his own age. Then again, he's just 12, about to turn 13 in April. The things he does, just ticks me off 24/7. Spend a week with him, you'll want to return him. He's just a waste od everyone's energy. There's no trying to get along with him, because he'll never cooperate.
Both of my siblings won't even let me be the big sister I am supposed to be. From my whole family in general, there's no love nor affection shown towards me whatsoever. So, I'm starting to just stop giving them my attention. I'm a good person. I have a good heart, and I don't deserve any of that. And I am sure that you don't either. It takes the wrong/nasty people to make the nice/good ones have a bad side.