“那时我才知道，我在这小屋里只呆了不到半个小时”的英文表达为？

Only then did I know that I had just stayed in the small room for less than half an hour.

那时我才知道，我在这小屋里只呆了不到半个小时
I didn't know that I had stayed in this cabin for just less than half one hour until then

I knew until then that I was staying in the small house for only half an hour.

Till then did I know that I only stayed in this small house for less than half an hour

At that time, I only know that I am in this small room only spent less than half an hour

at that moment i realized that i had stayed in the little house for less than half an hour.