what should I, f18, expect going to a gynecologist for the first time?

for context, my period stopped all together in may, and at first i wasn’t worried, as my periods have always been irregular. but now, i finally made an appointment a few weeks ago for mid november.

now, im very nervous about the process. i dont know what to expect, so I have a few questions:

are parents allowed to be in the appointment with me? will they make them leave during personal questions (sex life etc)? will i have to enforce my mom leaving?

what tests do they usually do? does it hurt?

what do i need to do to prep before the gynecologist?

will they drug test me?

thank you all so much for reading through this!! id love some advice!