There's nothing like a little time at Oshkosh to get the building juices flowing again. Having been building and flying airplanes for quite a while now, along with doing my own maintenance on my certified airplanes for years, I have to say that keeping certified airplanes going is more frustrating for me, mostly from a cost perspective.
However, I share in your frustration with building, let's call them "mishaps", that can make you feel like you took one step forward and two steps back. My most recent mishap was fitting the wings for the first time on my RV-12. The sawhorse that was holding the wing (a Home Depot fold-up type) collapsed outward when the plane moved while I was getting the flaperon torque tubes fully seated - and the wing tip hit the floor. Talk about disheartening. [a separate, lesson-learned here is that the HD stands need to be locked and then deck-screwed into position - otherwise, use a solid, non-folding stand - or better yet, a fancy-schmancy wing cradle, a la Joe Dallas...and Joe, you know I love your stand]. So now I've removed about 200 rivets and I'm ordering parts (not expensive) and I'll spend some time reinstalling said parts. And I'll have learned a lesson.
But in the end, no matter what your skill level, you'll likely make mistakes. You might be coached that some folks just don't belong in aircraft building, like it's some mystical arena for the gifted, but it's really not rocket science, and even rocket science is just a bunch of math and engineering problems rolled up into something bigger (and I know what I'm talking about as I've been an engineer building all kinds of high energy things for decades). Just take it one step at a time (Van's does a great job of this on their drawings), but don't give up!
It's the learning and the building process that makes experimental building what it is, an educational process that leads to fun flying. Just get someone to help and advise you and get back on track.
Hang in there man - and stick with it! You'll be so happy you did and will have the biggest grin when it's done.