Underproofed?

I have made sourdough a few times now. My starter is about 6 weeks old. Seems pretty healthy as it triples in size after a 1-4-4 feeding of 70% bread flour/30% WW flour.I feed my starter before going to bed.Start in the morning with 60 Minute autolyse prior to adding starter and salt5 1/2 - 6 hr bulk ferment (including stretch and folds) at 80* (oven with light on)Pre Shape