Welcome Kevin! I’m in Grade 3, and guess what - I often feel overwhelmed. I’ve decided that’s just part of the journey! As for tips on managing that feeling: I try not to get too focused on a single skill or song, realizing that practicing in 10-15 minute blocks is much more effective than repeatedly spending 30-60 minutes on a single thing. (Yes, I know Justin teaches this, but…. 
) I also set things aside when I hit a plateau in improvement, and come back to them later - for example when a new song requires that technique. If you’re interested, there’s a great book called Learn Faster, Perform Better by Dr. Molly Gebrian that discusses the neuroscience of learning. She’s a professional viola player (as well as a professor). Here’s a great summary from our own @ziggysden.
See you around!