I have been diving reasonably deep into the Tool For Thought category over the last two years, but have yet to see notegarden in this space. I concur with the spend your effort on marketing not development.
Look into tools that both do the same and more:
- Obsidian.md
- RoamResearch.com
- Notion.so
- Remnote
- Readwise.io
- Anki
Also the copy overall could take some overhauling, there are some errors and stuff that takes you a bit out - perhaps hire someone on upwork to check that up.
With regards to team, maybe figure out what your cutoff point is for calling it quits. If you have been working on this for 3-4 years, without many users, three persons, what are the signals that you are working in the right direction? Figure that out, commit to some numbers and dates, and strategize based on those numbers.