Your quilt is beautiful... it’s hard to imagine that you actually need a class - you’ve already nailed it, girl!
As for the missing block. Been there done that! Places they “hide”... folded up with backing or batting, in a pile with another project, and i’ve even had one go home with another quilter who sat near me at an all day workshop! 😊 And yes - you could make a replacement block, but you know you’re gonna find the original block once you do!
Good luck finding that block. Again, it’s a beautiful quilt!