Congrats on the traction. Somewhat unrelated, but it seems a lot of bootstrapped success stories are job boards.
The biggest problem though is still bootstrapping the demand side (job seekers) of the platform (supply side is fairly easy, as you can even handpick the initial jobs).
We (https://swissdevjobs.ch & https://devitjobs.uk) started with articles how to migrate from other countries to find a job in Switzerland / UK and at some point the organic traffic picked up (but it also took years, as in the case of japan-dev).
And I niched down hard.