I don't care nomore

My mom died when I was 7 bout to turn 8 in 3 days(I'm 14 now. She was murder in my face. 
I really do miss her sooo much.
I don't know why but I just don't care no more every time something happen that I would get mad about I just let it be.
When people buy me stuff I say thank you but I really don't mean it. The only person that I loved was my mom and someone took that away from me.
I can't get close to nobody 
I always make sure people are ok and nobody makes sure I'm ok 
People tell me "you're holding the door open for someone and get mad when they don't say thank you" 
Every time someone say something I just be like I don't care and I really don't.