Please answer me I am hopeless

Yes, my mother is now a Japanese citizen since 2014. She told me that she already went to japanese immigration and they told her that she needs to apply eligibility for us and support documents that will show their financial records if they can really raise us. About the age requirement, i am turning 20 this November that is why we are making it possible to get our visa and eligibility before I turn 20. About the immigration lawyer, yes we will apply for it. I will tell my mother about this. By the way, we already consulted to a private lawyer but it seems he just wanted the money because every time we ask him some questions, he keeps saying "just trust me, you cant go to Japan without having the same surname with your mother. We must take a case to change it as soon as possible." Then we found out that it is really not required to have the same last name so we cancelled him. Thank you everyone for answering me 😊 I appreciate it very much. If you guys still have an advice or opinion, pls comment it down. Thank you, again! God bless us all 😊❤