I once did a short comic where one of the pages used dot techniques similar to this. No where near as detailed, however haha shenaniboom.deviantart.com/art… My wrist hurt afterward after working on that so I commend you on the effort it must've taken!
I see. It looks good anyway! Maybe you pushed pen too strong, or maybe you've spend too much time at one sitting. For this artwork of mine, I tried dotting for an hour and then have a break an start dotting later or in another day. It helps me avoid getting bored, but it needs much more time to finish a drawing.