How to let my mom to let me act?
Are you in a theatre group? maybe some plays at school? She will let you if your any good. Probably doesn't want you to get your hopes up. that business is tough. I am surprised she won't let you unless you plan to make this your living.
ask her why she wont let you act and then try to fix that prbole.. why wont she let you act?
Show her that you have potential, do a skit for her.