I work in a research group of an architecture firm that contains around 4-5 developers at any given time. We develop a lot of the in-house architecture software, and our skillsets range from C#, to Java, to PHP, to most of the major web languages (like JS, HTML, SQL, etc). We are definitely a group of transdisciplinary skills. Our work involves not only working on software, but also communicating with the architects within the firm to better improve current software and develop new tools.
As the number of developers increase, and as the result of us just releasing a new piece of software for commercial release, we noticed that we definitely need and definitely will need a new way to manage our team. That is, to coordinate projects, to monitor/track changes (git, or any version control), to manage features, and much more. As we are a team of many skills, I am the only developer in the team that came from an actual software development team. Tools I used in my previous gig was project management software like JIRA, Confluence, HipChat, git, and more. However, my previous company was a firm of 100+ developers, while this team is only 4-5, so using JIRA, for example, would be overkill.
I am in need of some help and suggestions. What type of project management software can we use to track the things I listed above? What type of workflow can we adopt, i.e. Agile, Scrum, etc?