I've spoken with the teacher.
I started by apologizing for the missed classes and not working with her on the matter, but she cut me off. She said she understood that I chose a different subject. I explained it to her that I didn't make a choice: I need both her classes and the other subject's, but there's a problem of time management on my side because of the overlaying timetables.
"Well," she said, "I understand, but I can only teach someone if they're present in class. If you aren't, I can't give you the time you need. You understand that learning sometimes takes continuous practice". She's a head of the division within the department, so she could be pretty busy.
Still, it solves nothing. I'm still getting no formal classes, which is strange, because how else would I catch up?
She suggested that I look into mixed groups, which are formed out of students from other departments if they have to study languages.
I'm going to have to speak with the dean. Then I'm going to speak with the teacher of the other class I'm missing and check whether there are similar complaints on her part. The latter teacher was patient with me last semester, when I skipped a whole lot more, so I'm not too worried, but it's better to check.