I'm 45 and I can't decide what I want to be when I grow up . . .

I am too. I am 40. You don’t have to have a trade or degree to be happy. You could get a list of every career and cross one off at a time. You are ahead of your peers who are $200,000 In student loan debt. You can learn lots on YouTube and online moocs.

It’s painful for me to live in poverty like I am now. I’m the first person in my family history who has ever had to use food stamps and depend on the government for help. I want to stand out and be successful! I think having a degree would at least help me feel like I “tried.” I’m lucky enough right now that my rent is super low, and I could afford to go back to school for awhile. But I am having trouble choosing what to focus on.

Well,you say you are a medical transcriptionist. Does being in the medical field interest you?

Like read into the fields you are interested in deeply. Talk to professionals in those fields, maybe see if you can job shadow

There isn’t much math or chemistry needed for anthropology, English, or genealogy.

As for education, one school of thought shared by several groups of thinkers is that everyone is a genius at something, but often our regimented society, parenting and education interfere with us finding and developing it. I’d say it’s well worth looking for, especially when one’s feeling the call like you are.

Taking a look at what serious work/thinking is like in each field you’re interested in is one way to tell whether an interest is just an interest, or something you’d actually want to do serious work in. University courses are great for that, but since you lack the funds, libraries and the Internet provide plenty of access to almost every topic, if you can organize yourself to study them. Online course syllabi for courses often have reading lists that for many fields can often provide the equivalent of a college course if you do most/all of the readings for such a course. And nowadays there are also many free online videos of course lectures.

However I think that realizing one’s genius is often a matter of tuning into one’s intuitive knowledge and developing self-awareness, and allowing yourself to want what you want, which also happens to be a good practice in any case.

It happens. Some people get to 50 still asking the same question.

“Anthropology, English, Genealogy, Medicine, and Education,”
All of these have a common point and that is dealing with People..helping to solve, to explain to teach ,and to Research.
The situation that you find yourself now to me looks like you are been prepared for Social Work and to learn the problems of Society.
In order to prepare you for YOUR vocation you are going through the rungs of what a destitute’s path that they might go through, in order to fully experience and understand that Human Condition.
I suggest you volunteer to causes such as Food Banks etc to get a feel of how you feel in being a part of the solution to Poverty etc

Each person has his own Vocation.
Their is one direction in which all space is open to him/her.

If you confront obstacles on your path, then you are on the wrong path, BUT if the path is open and allows you to go ahead without obstructions..then that is the right path for you
and you will know and feel it.

If you have good people skills you might consider becoming a nurse. If not then a job working in a clinical laboratory (as an MLT or MT) testing patient specimens.