You said your drained after back, but want to add squats? I'm sure that was a typo.
I suggest, moving forearms to leg day, since al you do is squat. Throw in some lunges, single leg squats or something with squats.
You could also throw rear delts on leg day if you decide to only do squats. Would be designed almost like hss-100 for shoulders.
Not sure what arm day is, so I guess its just biceps and triceps? No other shoulder work other than the ohp. So it could work.
A lot of people do the "strong lift" last. Personally I think you should do your strength work first. Try doing deads first instead of last one week and go from there.
Try to train your work capacity. Increase your ability to train at a higher volume.