OBGYN appointment

Hi girls, I’m 16 and I have my first obgyn appointment tomorrow. My mom made the appointment for me with her OBGYN who is female. She said I was having bad periods and looking to get on birth control. I’m just scared and not sure what to expect. I read online that you get a metal thing stuck inside you, have to put your feet up and they poke around down there. My friends have also told me some crazy stories as well so I’m terrified. Please help me!