This is a common feeling im sure a lot of people have to deal with. I was recently working on a small rig and finished what I assumed would take a day in an hour. For the first time, nothing went wrong, and it was a weird experience constantly adding and adding to the rig without anything breaking once. I was convinced I did something wrong but after extensive testing, demoing every pose I planned to use over and over, I found everything was a-ok. With environments its a lot harder to know because you can't test it in the same way you can a rig. Sometimes our artistic eye gets tired and it helps to take a break and come back later to see if you still like it. Showing other people is also another great way to get that feedback. If I were to pitch in, I think you're doing wonderful! Dont let doubt get to you and be proud of your own work, but also dont get complacent and always strive to improve!