Getting accurate estimates on the production time is always a tricky task, especially for really small teams. However, given what you have in store for the game, I'd say that's absolutely understandable and you shouldn't feel bad about taking the time you need :)
I appreciate your openness about it as well as the time you put into your work and can't (but will patiently) wait for future updates, because I recognize that this game has a lot of potential :D