Student health insurance no longer possible after a part-time job?

I'm enrolled at a distance learning school, so I'm basically between pupil and student status. I previously had family insurance and then took out health insurance with TK about a year ago due to my age. I only had to pay the student contribution of around €150. In addition to my distance learning course, I only have a mini-job where I accidentally exceeded the salary limit for a month. That's why I was registered as a part-time worker for this one month. After that I was