Tongue Piercing!?? Please Helpppp?

Mmk, so. In January,, i was diagnosed withhh Hodgkins Lymphoma and i got chemo for about 4 months and May was my last chemo session. I had scans like a month after that and they were clear, and a couple weeks ago, i got more scans and those were clear also. so basicaly, im cancer free now. The doctor said my immune system is like almost normal but its still a LITTLE bit low. My aunt was going to take me to get my tongue pierced for my birthday (i turned 15) but my mom said no cause my immune systems too low and its an 'open sore'. i want this SOOO bad. I know all the risks and stuff but does it make a HUGE diffrence that i have a kinda low immune system? ill take all the precautions and try to make sure it wont get infected. Please help mee persuade my mom haah. thanksss<3