Why can't my mom be more understanding?

well im 17 years old and lately i have been having a very hard time with my mom. She tells me that i can tell her everything that is happening to me and that she will help me if i have any problems. we she lied because she makes a big deal about everything like i told her that sometimes when i hang out i would hang out with a boy and we would make out that was it she was cool with it. then one day i get home at 2 am she flips out and i have came home later than that plus i called her through out the night just so she knows im ok and she accuses me that i am hanging out with boys and doing stuff but i tell her im not like that but she doesn't trust me. and i can't tell her how i feel about it because she thinks that im disrespecting her. She thinks that she is always right even if she is wrong you can never win and everything i say against her word she thinks im challenging her. Also, i sometimes get really depress or angry for some reason but i have no one to talk to and i want to tell her but she just tells me that im being dramatic and stupid and that i can't be because im young. i love my mom but little by little i feel that love disappear and i don't want it to because i know whats she's been through. (she use to have cancer but she is cured but she is not the same) Now i cant take it anymore i just can't my dad gives me advice on how to deal with this problem and i try but it is not working i really need help also she is not going through menopause.