Don't let it stop you, Duh... someone may want a map that covers that much area; doesn't matter if the CMs are building something similar or not.
Your results look so good so far that you should not stop, no matter what.
FWIW, there is ALWAYS going to be someone working on a similar project somewhere... always. The reason for you to work on your own is because you want to, because you want to build it yourself. It's not a race, it's a challenge... it's a test of self-achievement.
Build a map because YOU want to see what it's like to build it, to have that pride. And every map you build is practice for the next map, and the next map after that, and after that...