Thanks for the extra pics!
270lbs is small?
I'm around 188 at the moment...
My goal for the end of the year is 195
My back is pretty small, even though it is really strong. I do lat pulldowns of 300 lbs, One Hand Rows with 125 lb dumbbells (since that's the max we have at our gym), and One Hand Row machine with 4 Plates and a 25 lb. It's quite odd actually. It's by far the slowest muscle that grows for me. I'm thinking that my strength is due mostly through neurological factors than muscle factors for my back.
That's really quite strong.
Maybe your form is a bit off? (No offense intended) Otherwise i don't know why you're lats won't grow.
Try to stretch after each rep and go over the full ROM.
Also, do you do pull-ups? Imho the best exercise for lats, especially when combined with loaded stretching at the end. I think you know how to do them correctly
Have a good workout,