Here's the current official GTD definition at: https://gettingthingsdone.com/about/This leads me to the terminology issue I keep having, between two uses of GTD. There's "GTD" as the name of the overall process of managing your work, and there's "GTD" as the name of the project/context/action lists part of that process.
I keep using the term just for the lists, plus maybe the calendar, tickler, and a few related things, and it sounds like you're doing the same here? But arguably your use of mindmaps is GTD. If someone is using Nirvana and mindmaps and Microsoft Project and JIRA and Evernote, that's arguably all GTD--whether it's GTD is determined by whether they're using them in accordance with the GTD process. Or more or less in accordance.
Your mind is for having ideas, not holding them. That’s why David Allen created Getting Things Done®. GTD is the work-life management system that has helped countless individuals and organizations bring order to chaos. GTD® enables greater performance, capacity, and innovation. It alleviates the feeling of overwhelm—instilling focus, clarity, and confidence.