This might sound mean but, why not play a bunch of crap VNs? In fact, not even crap ones, as such, but just any from the newest section of itchio.
If you can say 'my game's going to be way better than 90% of these' then that should help with confidence. And if you can't, think about why, and what you can do to fix this. For motivation, you should consider that these games have been released and yours won't actually be better until it's also finished and public.
Don't sweat about perfection. No dev ever reaches this bar because it doesn't exist. If you just ensure you make a game that satisfies you then other people are guaranteed to enjoy it too. The absolute worst case scenario is a couple of play it, don't like it much and then you move on to your next game with lessons learned.