You are indeed overthinking it, but I understand the impetus to do so.
If you want to teach, you need to major in something that you can teach. It would also be ideal to major in something that is actually in demand in the state in which you want to live. The Department of Education [maintains a listing of teacher shortage areas by state](https://www2.ed.gov/about/offices/list/ope/pol/tsa.pdf).
Some states have designated almost every subject to be a shortage area. Generally speaking, mathematics and science education are usually the two most common shortage areas, but English and history are also shortage areas/critical needs in some geographic locations. In some places foreign languages are also critical needs areas; most school districts want someone who can teach French, Spanish, or German. You know French and Spanish, so those are potential majors (you can skip the language classes and go straight to the literature classes).
Each state has guidelines on how they certify teachers, but on a general level you need to major in whatever you want to teach. So if you want to teach French, you need to major in French education at a school that offers you the curriculum necessary for licensure. If you want to teach history, you have to major in history. You can’t, say, major in anthropology and decide you want to teach French later.
However, if your goal is to get a JD then one option is Teach for America, which will allow you to teach for two years (often outside of your subject area) in an underserved community. TFA is very competitive, but serving this way actually looks pretty good on law school applications. Quite a few friends of mine did TFA and followed that by going to business, med, or law school afterwards, including a friend who went to Yale Law. You don’t have to be certified or have majored in education to do this.
Another thing to keep in mind, though, is that your desires and wishes will evolve over time as you take classes and experience things. I am currently in a career that I would’ve never considered in high school, as are many of my friends - I had never even heard of it before going to college. You might have a part-time job or internship that exposes you to something new. You might take a class that makes you fall in love with a major you hadn’t considered. Even just between now and next April your ideas will change - I changed my major from political science to sociology just in the three months between graduation and the beginning of college (and then changed it again in the spring of my freshman year).
Also, the law market is terrible. Do a Google search and check it out.