There are many ways you can impact immigrants living in the United States. A few thoughts come to mind:
1. Have you considered teaching? Many immigrants and refugees attend public schools within the United States, and there is always a need for English as a Second Language (ESL) teachers. You would be impacting immigrants through education while applying your bilingual skills. You may even have the opportunity to teach math to ESL populations depending on where you work and the school's needs. Public education is a huge social justice issue in our country.
2. Many non-profit or non-governmental organizations exist to advocate for social justice and have a variety of personnel who work for them. A quick Google search of "immigration nonprofits tennessee" led me to the Tennessee Immigrant and Refugee Rights Coalition website. Here are some of the jobs and internships they're currently hiring people to do: https://www.tnimmigrant.org/career/.
3. Working in higher education as an admissions counselor might be of interest to you as well. Most colleges and universities are trying to increase the diversity of their student bodies, so they're making a concerted effort to recruit historically marginalized populations (immigrants, or international students, included). The admissions process can be daunting, so you could provide support to students and their families. Another option in higher education would be to serve in an institution's cultural center, advocating for inclusion on campus and supporting immigrant students throughout their collegiate journey.
These are just a few ideas. At the heart of whatever you do is your passion for and dedication to immigrants in the U.S. Your degree is only ONE aspect of who you are and how you can make a difference.
Best of luck to you as you explore your options and discover the possibilities that await you!