Welcome aboard, @toobiwankenobi 
!
Thanks so much for including screencaps and complete commands. This helps a ton. I'll do my best to help out, but some housekeeping first - because this post was split from another post, I'm not sure whether you generated the title. If so, please be more topic-specific in future. If that's not your title, sorry! 
.
Your denoising-stats visualization suggests that sequences are dropping out because they are failing to merge. 
DADA2 requires ~20 base pairs of overlap between forward and reverse reads in order to join them. If you're working with a longer amplicon, it's possible that many of your reads have insufficient overlap to merge. There's a good discussion of this in these posts.
Once you've determined whether this is your situation, there are quite a few posts here that discuss possible next steps. Let us know if you have trouble moving forward. If you think this is not your situation, please share further sequencing details so we have a little more to work with.
Thanks!
Chris