If it were me I would rather be bootstrapped but take a little longer to get there. To me there's no point in swapping a boss for an investor.

I see you mentioned that you already have videos & training materials for users. I would start to document how you do the onboarding in person so you can teach it to someone else. Don't underestimate the value of high-touch sales. It shows that it's working for you.

With you currently having a job, you could invest your current income into rebuilding a new (non-WordPress) version. If your current version is on WP - do you really need a team to create your new version - or just someone contracted for a few months & then on retainer.

Once the new version is up to the same feature set as the current version - migrate users over. Then pour your income into streamlining your business, hiring employees etc.