I’m never going to be good enough for my mother. I just really need help

I’ve always been a disappointment to my mother. Even when I was younger I couldn’t make the cheer team like she said I could, or the volleyball team, or get a part in a musical, etc. and I’ve always only had “okay” grades and my mom makes me take all these college classes and im so overwhelmed and I cry every single day. She stresses me out telling me I need to know what my career is going to be so I can major in it but im not even going to get into a good college because I’m not smart enough. My cousins and my brother all have above 5.0 GPA’s and I only have a 3.0. Im always going to be the family disappointment and I just don’t know what to do anymore. I’m only 17 and I have way too much stress on me. I just want to be young and happy like the other kids. I’m sorry I just didn’t know where else to post this. I’ve been bawling my eyes out the whole time writing this. I really need help. I need this to end. Please help me. No one cares