Help needed with pull-ups

There's a lot of great advice here! You've got multiple suggestions here that are well worth a try. In addition to the controlled negatives, monitoring rest between sets, and continuing good sets even as you get down to only being able to do one rep a set, I'll add two thoughts.

1. Different grips for increased assistance as you go along - when your lats start to fatigue during your sets, you can throw in some chin-ups to get some assistance from your biceps or some close side-grip pull ups to shift some of the focus to other muscles for help.

2. Do a form check! It's not a mark of shame -- even after years of pumping out pull ups with ease I recently realized I'd gotten complacent and stopped activating my lats for too many sets to count. Make sure you're not hunching your shoulders up, make sure your grip width is right (I overfocused on wide grip pull ups to the point where the muscles above my lats have taken over and made it harder to activate those big lats I should be using to further increase my numbers/effectiveness, resulting in an odd stall that's forced me into doing more lat focused exercises so my body gets used to relying on them as the primary force for pull ups), etc.

On top of that, sometimes we use too much momentum near the top and end up doing some decent metabolic work but take away the strength building we need to increase the full range of the muscles we're working effectively. Sometimes we barely get our chin over the top of the bar instead of fighting to push our chest up to it, etc.

There are a lot of good videos about pull up form that generally say the same thing, but here is an Athlean X one from a physical therapist that does a good job of breaking things down . Sometimes it's just these little adjustments we weren't paying attention to that are holding us back!

Also, if you're having trouble feeling your lats activate in order to use them properly during pull ups, here is one of the classics from mountaindog1 that helps you feel and jumpstart those lats into doing most of the heavy lifting.