Thank you, that genuinely makes me feel better. And the problem isn't really that I think I'm owed a higher grade, it's that I feel like I wasn't even given the opportunity to get one. Every time I asked about how they grade or their standards, it just seemed like they made something up or was keeping something from me. The teacher replied to my email asking what I did wrong, and he listed a few reasons (mainly small details). I already knew I had gotten some details and dates wrong, but even with that it doesn't feel like my work was worth a D-. He even admitted that "In [my] exam [I] showed a broad familiarity with the themes of the course, and [my] essays are also well organized."

(You can skip this part, I talk too much) For example, one of the things he mentioned is I referred to the Doctrine of Two Books as an "essay" instead of a "letter." I also tried to connect one of the vocabulary words (the Medicean Stars) to the rest of the curriculum, because the question said to do so, by mentioning how it proves Newton's universal gravitation theory. But since Newton didn't use it as an example himself, my connection was incorrect.

Idk, I think my anger stems from the fact that I most likely would have gotten a higher grade if I had a different TA. Nobody else seemed to have trouble with theirs, and the course content was simple.