For one, ya talk a lot kid...
Secondly, hand fatigue happens, (mainly to those who don't paint ever).
Paint every few days, and it goes away as your hand gets stronger. I have a callus in a circular shape on my index finger from NY fats. If you get fatigue, switch fingers(or hands). I usually use my middle finger and thumb for fills, and index for outline. Giving up at the end of a piece really destroys the whole outcome, so stay focused. If you want better letters, draw more!
I use Rusto, and sekt adapters with an NY fat are pretty much all I use(lots of writers use this combo).
Try and not think about how clean stuff is, just do it fast and steady and it'll come out clean with practice.
I'd simplify the E, and keep that bottom bar uniform instead of flared. Keep the E's structure like a 3 instead of it getting broken into bars that barely connect at the bottom. The 3d and control need work, and I'd keep the S smooth and uniform, instead of making it narrow where the bars connect.