HELP with stress school and everything else?

Ok im freaking out im in the 8th grade and im getting so muh homework and when i get home sometime i will blow it off and do it in homeroom the next morning and now i have missing ignments in sime cles and my mom is yelling at me and im grounded and some of my teachers dont accept late work and my mom does not understand that and she wants me to have a GPA of at least 3.5 by the end of semester which is next week and im FREAKING OUT and I cant sleep and i dont know what to do PLEASE HELP ME