Piercing

I want my septum pierced but my mom says no. She says If i get one she’ll kick me out or rip it out. Septum piercings are easy to hide but i also dont want to go against her wishes. But im also 19 and have a huge tattoo on my arm (she was NOT fond if it she stopped talking to me for a week and treated me like i was the worst kid ever) but im working and going to school i dont party or do anything crazy so i feel like i should reward myself but i dont know yet. :/ pls help !