Fit check: happy baby original carrier

Help: my grumpy lil 10-week, 14lb guy both fusses like crazy in it, but it’s also the only way he’ll fall asleep. The belt is fastened directly below my bust and cannot go any higher, but it does sometimes ride down when he’s in it. Not sure if I’m doing anything wrong because he’s just fussy most of the time that he’s awake anyway right now.

I also have a ring sling but cannot for the life of me figure out how to work it. I have watched all the YouTube videos.