First - take a picture of your original map, so You know how to go back ~
Second - don’t get too caught up with islands you see online that don’t match the type of town you like. Not sure if that makes sense.. but I’ll try to explain. I saw some beautiful pictures from a island that had a streetstyle aesthetic. It was gorgeous! So of course I wanted to make a urban city. I started- but it didn’t turn out that great, clearly because I know this is not the type of town I enjoy playing in. I only wanted to make it because it looked good (like AMAZING oh my god that was some good designing). This caused me to terraform again.. and again.. and again. Because the result was something I got bored with even tho it looked alright, but I felt like a project rather than something that resembled my own.
Third - don’t stress yourself. It doesn’t have to get perfect. Spend your time with your villagers, fish, catch bugs, decorate as the days go by. And suddenly an idea will pop up. And remember that you can always terraform back to how it used to look if the idea didn’t turn out like you wanted.
These are my tips, I didn’t read the responses before me, but hopefully it comes in handy.