What's wrong with my mom?

I mean sometimes i really feel really sad when my family members fight against each other. my mum, i don't know what is she thinking but she never understands me at all! I am totally sick of that! She never understands anyone and she always instill low confidence in us by saying other people's children are so so so much better. Then, she's always caring of her other relatives more than towards me and my sister, seriously. She would spend thousands on them but when i just ask for a new pair of shoes and she'll act as if i've lost my mind! She'll go on harping about how pretty others look but she commented so much when i purchased my first heel which is barely an inch! I don't know what's wrong with her? I mean im a teen and i know what im doing. She never cares about us but she wanna know what's going on in our school. When we tell her, she just don't get it and is not interested and she started talking negative things. That's why i kept secrets from my mother. What the h.ell she cares? And if im fighting with my sister, shell barge in. Not trying to break us up but making the fight bigger. I mean we're not fighting with her so back off! We'll be ok after a while. But she's not going to let go! What is a mum that doesn't understands her daughter>?????