Thoracic Spine Mobility Exercises for Better Overhead Press

My overhead press has been stalled for months and I think it is because my thoracic spine is as stiff as a board. I cannot seem to get the bar into a good overhead position without arching my lower back excessively. I have a typical office worker posture which I am sure is the root cause.

I have started doing foam rolling on my upper back and some T-spine rotations. Are there any other high impact exercises I should be doing? I have heard that bench T-spine extensions and cat-cow stretches are good for opening up the chest and upper back.

I am also wondering if my lat tightness is contributing to the problem. Does anyone have a good stretch for the lats that also helps with shoulder overhead position? I want to get that 225lb press this year but I need to fix my mobility first.