>Has anyone else been in a similar position? How do you ensure you're not making foolish mistakes that you've become blind to?

If you are the only developer, well you still know the pain points in your own code.

And its far better to have something correct than nothing at all, even if its ugly and/or slow and/or hard to maintain or modify.

I often rewrite my code if i encounter limitations. Refactor often and write tests (I'm too lazy to write tests, bad, very bad, bad!).

Also read a lot of others code. Helps you grow and fill in blindspots.

You have a larger burden than usual to facilitate your own growth and knowledge expansion. Because you are alone.