I love the time bubble concept, however, I feel like every patch/expansion exists within its own bubble. And each of those bubbles line up to make a bubble stream.

(1) (2.0)(2.1)(2.2)....(3.1)(3.2)

The amount of time you spent playing exists in a "patch bubble" and they like up to make a smoothly flowing time line.

Back to the original question, I like to think the main games (ARR and hw) span 6 months and every patch exists over the span of 1 month.
Calamity- ARR =5 years. Arr=6 months. 5 arr patches =5 months. Hw=6 months. 3 hw patches=3 months.
So you've been traveling around for 1 year 8 months. So the calamity would be 6 years 8 months ago.

P.s. I'm probably completely wrong about this. I just like theory crafting.