Birth control

Okay so in a few days I go to have my yearly physical and I wanna start birth control because of my period cramps. I usually miss a few school days out of the month and sit in my room and cry and throw up from my period and my friends keep telling me to try birth control. I really wanna try it but I also don't want my mom to think I want it because I'm having sex even though I kinda am every now and then with my boyfriend but she'd kill me if she found out. I wanna ask my doctor but I don't want my mommy to judge me. Any tips? And are there any that you recommend I ask for to make my period shorter (it's usually 8-11 days)