You have a good upper back to me, proportionately. The hamstrings and glutes definitely need to be brought up, because they’re going to keep shrinking as you peel fat off and they’re already small in comparison to the rest of your presentation.
You look like you would benefit most to put in some serious work on RDLs & GHRs. If you don’t have access to a GHD machine, look up Nordic Hamstring/Leg Curls where you wedge your ankles under a rack or gym equipment, in a Pulldown station facing away with a broomstick to push off/stability, or have a partner hold your ankles while you are kneeling on a mat.
The Nordic curls are a harder heavier movement usually than using a GHD machine, so be warmed up & hydrated well for them so you don’t cramp up or risk a hamstring pull. You can do a push-up off the floor if you are too weak to start the movement without them - focus on a controlled tempo negative after the powerful contraction up.
The RDLs will hit the glutes & erectors hard along with the hamstrings, and they will use less load than a proper deadlift so your core will grow less, and they also takes the quads out of the equation (which you already have plenty).