I hate my brother!!!! (younger)?

Ok so today OS my 16th birthday...and I have 6 Bros...I only have 1 older though...ok so the one I hate is in 7th grade and I hated him all my life. I tell ppl we aren't related and whatnot. I've hated him cause he steals my stuff and my mom doesn't give a fck. Today was my bday and I was hoping it would be nice (I'm a girl BTW) but I didn't get anything...instead my bro I hate got a Nintendo. I didn't get anything and he gets things even though its my day? My dad told me he would take me out to eat...I was all ready to go...I was watching t.v waiting for him and he didn't come...he called me saying he had things to do. I couldn't find my bro and I was just informed that my dad took him out to eat. Why does this happen on my 16th birthday? I don't feel special and I'm not a bad person at all. I feel neglected and bad...help?! Why does this happen to me?!!!