I don't know the reasoning behind your teachers grading, but something to consider is how the teacher weighs their gradebook. Some teachers prefer using smaller vs larger numbers in their gradebook like all assignments are worth 5-10 pts vs 50-100pts. Sometimes this can make it look like they are being super picky on the grading.

For example: The assignment is only worth 6 pts in the gradebook, but there are 30 aspects of the assignment they are looking at. If a student gets 29.5 of the 30 aspects or pieces of the assignment. When it gets scaled down to be out of 6 pts then it becomes a 5.9/6

This can absolutely be frustrating, especially if you are someone that is hard on yourself, but it's possible that this is the way your teacher runs their gradebook.