Hi Hazel - my DD is 2 weeks younger than Hannah, and her routine is almost exactly the same as Hannah's. The only thing I can think of is that she's ready for longer A time. My DD just went from 2h to 2h15m this week. I have read somewhere that 30mins means overtired, but seems unlikely given your routine and how well she sleeps...?
If she was doing 2hrs a couple of months ago, that means she can go longer than 45 mins, so it's probably just a matter of tweaking her routine. Don't worry, take a deep breath, the solution is just around the corner. I've felt like you on several occasions, and I've learned to just give myself a break, stay optimistic and keep on adjusting until the routine is working again.