IMO i've been where you are. CTOing all-in-code. But i'm not sure i found an immediately obvious way. Because it was not just my way, it has to be teams/startup's way.
Having some mostly working software that can be used as prototype and show-of-concept is good. Very good. Don't throw it away. Keep building it, Maybe slower.
In paralel, try to find what really you all want. And What is missing. Involve some possible wanna-be users. (Who are the users? Are they just one kind - or there is some completely sidetrack group that has not been forgotten? e.g. admins? statisticians?).
What aspects are weak? Is it about features, usability, product, technology, customers, marketing, maintainability, proper spec, some-future-in-2-years, shiny looks, bells-and-whistles, whatever. Then Prioritize those. Or maybe first Prioritize the aspects, from business perspective, and then find how much each one is covered or not.
We can talk more if u want. Even if only helping you identify your own problems - or just fears.
Have fun.
