there is no need to be nervous at all.
Every developer started at some point, and no one has been perfect right from the scratch so far (not even the top-dog developers)
There is just a HUGE difference whether a game got good basics where constructive critics can be based on - compared to crap games, which are just so worse, that every try to fix issues will make the game more broken.
You need a good foundation to built on - and your game is solid.
Everyone who knows me, also knows that i don't hesitate to trash-bash games whenever they are worse. But i am also honest whenever i like a game.
Your game is definitive within the second.
Just keep on going - listen to people, but take care not to easy try to please all - trying to fullfill every kink, even for the smallest groups never worked out so far - in neither game.
Reality has shown multiple times, that whenever you please one group, you will also upset 2-3 others. So live YOUR way, listen to people who are with you by that and do your vision - just ignore all others - better disappoint a few rather than upset many (except that niche would be exactly what you intended right from the beginning).
Be truthful from the start - changing things during ongoing project will end badly - the ones who disliked your start will probably not notice the change as they skipped and got you on ignore, whilst the others, who liked your game because of what is has been so far, will be upset and disappointed because of the changes.
But again: imho you did well so far, and i am keen on getting more soon (just really hope, the sandbox will not destroy the fun)
PS:
Sandbox can be ok whenever you just decide where to go and in what order to do different paths. Sandbox will ALWAYS suck, whenever you need to repeat scenes senseless to progress and whenever they even don't match together.
BAD example:
girl in school - bitching
girl solo - bitching (but you raise stats)
girl in school - bitching and reacting like nothing happened
girl solo - bitching (but you raise stats)
girl in school - bitching and reacting like nothing happened
... repeat that 10 times
then girl solo - she doesn't bitch anymore
girl in school - suddenly acts like she always loved you
got what i mean?
Sandbox always has a BIG risk of being inconsistent between different routes and stages. Just my humble opinion for a first game: avoid sandbox and just tell a story. Sandbox is REALLY hard to do well