I mean imo this looks just as nice as those requests. Even though its always good to challenge yourself as an artist, I think maybe your being too hard on yourself.
Also yeah, Art Block is a big annoying nope

i think this looks lovely! it's alright to be frustrated with yourself sometimes - if you thought everything was perfect you'd never improve. but you can't let it take the fun away from doing what you love. and you can't keep comparing current works to previous ones you were proud of, because trust me, you'll never move past the feeling of going nowhere. if you keep pushing yourself too hard you'll just hit a wall. sometimes to move past it you have to take a few steps back, whether it's doing something different or just taking a break from drawing.
personally, i think your art is always spectacular, whether it's lined or not. you could have such thick lineart there's barely any room left for coloring and i'd still like it! but i know that the self-critic is a relentless little douchebag. you are in no way failing as an artist - you never have! instead of getting hung up on moving forward, look back at what you made back when you joined. you've freaking skyrocketed and you keep climbing higher.
also, don't worry about when you get designs, trades, requests etc done. art is worth waiting for. none of us will be breaking down your door, no matter if it takes you weeks, months, or even years (coughs at self)
i hope you can move past this and start feeling better soon. just keep going, everything will pass eventually <3