Just curious, is there a reason why you decided to design your own storage format instead of reusing kdbx4?
It was actually interesting to work on a new file format. The version 1 was not formally versioned. I realised that for the version 2, I would need to add a version number to the file format. Of course, the world doesn't care about any of that, but I learned something doing it and am happy about that.
Designing things yourself is enjoyable and educational, so that is also a good reason.
The flipside here is that keepass format has passed quite a lot of scruitny over time, so the design should be pretty decent at this point (especially from security perspective). All that complexity that might feel overwhelming at the beginning also gives you room to grow over time.
As long as your code is well architected and your featureset somewhat conservative, switching out the storage layer shouldn't be too difficult if you ever change your mind. So from that perspective it makes sense to keep going with your own format as long as you feel like it, and focus on more important things.