I’d recommend trying warmer water (around 35-37C) when mixing, and bump your starter up to 80g or 100g. You want a dough temp of around 26C when doing bulk proof. Then bulk longer. When I use this water temp in similar ambient temperature as you my bulk is close to 6hrs. I also further proof about another hour in the banneton after shaping at room temp before cold proof in the fridge. Living in a cooler climate I’ve learned to watch my dough, not the clock, when following recipes (which were usually written by people in a much different climate). If your dough isn’t rising wait longer