Computer Science in K-12 education has had many issues over the years, especially for those who teach—creating lessons, finding resources, lacking official education in the field, keeping up with constant changes in the field, and feeling isolated. These issues have been mapped by various research efforts, where one found that two-thirds of teachers in the US lack a degree in the field. Contributing to the list of issues and their understanding can show a better path towards helping K-12 computer science teachers with their practice. Furthermore, the need to understand the specific context of computer science education in relation to a country is present. It further helps understand the specific needs that teachers have for their practice and professional development. We investigate the challenges in teaching computer science at the high-school level in Serbia while exploring opportunities for professional development and usage of reflection in teachers’ practice. We focus on teachers as the audience, which has to stay up-to-date in a fast-changing computer science field while facing numerous issues already found in the literature and voiced at teachers’ conferences, seminars, and workshops. Participants expressed having issues with content and ever changing nature of computer science. While they expressed the need to learn and improve, professional development courses are lacking which is taking the toll on the teachers. Reflection, although useful, is not used by everyone and mandatory reflection only adds more paperwork to already high workload.