Getting tested

I have an appointment with my doctor this Thursday so I can get a referral to get tested at the psychiatrist. I haven't told my mom and I am unsure wheter I should before getting the referral, if I do not get the referral I told my mom for nothing which I do not want.

I absolutely would tell her when I get the referral, but should I before I get the referral?

She always get super mad because I never tell her something, but I just want to avoid all the unnecessary trouble if my doctor doesn't give me a referral.