((((silversparrow))))
you're being so brave. i've been too scared to get one of those checks done, even though my doctor thinks i should.
could you ask your mum to come with you, but then wait in the waiting room? that way you will have someone safe afterwards, but not in the room with you where they might hear things you don't want them to know.
your fear about your dr finding out just by looking at you is not silly - a lot of people share this concern. but drs cannot tell someone has been abused unless that person reports it themselves. your dr will not look at you and find out. i promise you.
it is possible that some of your irregularities are due to emotional turbulence, though. e.g., with me - when i get depressed, my cycle stops for months on end even though i don't lose weight or anything. this is quite common. it happens also when we get stressed. so maybe that is an explanation for what you are experiencing?
if you scared about switching or getting violent or something (i'm so scared that i might lash out at my doc), then maybe you could tell your doc that this is really difficult for you and they will probably understand. my doc has been a lot nicer since she found out about the abuse stuff. now she knows to give me heaps of information beforehand, and then to schedule the procedure or test or whatever on another day. she has shown me what happens in a womens exam, shown me the stuff she uses and everything, so at least i can have an idea of what is going to happen.
good luck, darling

. i'll keep my fingers crossed for you.