Consider it from the point of view of a Christian parent. The child they love more than anything will not get into heaven. Their child will not be with them in the after life.
Seriously, because you believe in magic. This is what you do if she tries, you don't say anything about magic in front of the doctor unless he asks, you make up some story to tell him that makes you sound completely normal, and if they put you in a mental hospital don't misbehave, or do anything weird. Look, I knew someone who was crazy who I think might have done something similar to this. If they don't think your insane, the worst thing they can do is keep you in there for a few days. Just make sure they don't find anything wrong with you. Look, I have ADHD and I would never go to him and talk about poltergeists, spirits, psychic abilities and being a medium. It makes me look perfectly sane. No offense, or anything because it isn't your fault. You probably didn't know how your mom would react. There is one thing you can do if your experienced enough though, it is breaking the rule of three and only use it in situations like this but, I would try a memory spell. Can you make a psi ball? Because my old method was make a psi ball, and mentally, or verbally tell it the person's name and what you want them to forget along with all the usual end of spell stuff. Then let it go, send it towards the sky, and imagine it going to that person to make them forget.
Your welcome, hope it works; if it doesn't I have another spell that might work. Also, sometimes it takes twenty four hours for the person to forget. That's the longest it ever took me. For some people it only takes a few hours, or a few minutes depending on the person. Also, if she's already talked to the doctor you might have to do one on him too. If you know his name, you can picture what he looks like and use the spell on him too. It might be slightly problematic if your mom left a message on the phone, or with a secretary.
Oh, and when you make the psi ball be sure to use the words like you would a normal spell. Chant it several times until you feel that it's right, that's what I do.
My brother went to a mental hospital he's a little crazy any way my mom is cool with the fac I'm a witch because she did witchcraft when she was younger an she always said your gonna do experiments