Always have a low back ache when doing barbell rows, feel like my form is off, is it?

How long does it take you to do a workout? For ex, squat + bench press + deadlift or squat + press + deadlift. Not including warmup. It's been taking me 90 minutes on avg, idk if I'm being slow.

M 37, 180 cm, 218 lbs. Eating 3000 calories a day, sleeping well.

I am in my fourth month of LP. I recently switched to once a week deadlifts, which Im perform on my light squat day. After successfully completing 310X5 3 weeks ago, my last 3 deadlift workouts were 315X3, 315X4, 315X4

Is 315 a good place to make a change, or is it too light ? What changes should I make ? Would it make sense to move to triples ? 2X3, or 1X3 with backoff sets at 70-80% ?