run out of tranny oil while driving

[THE NEW GUY]

As the title says, my beauty ran out of transmition oil while I was driving on the HW 15 nord, in Laval, Canada this mornig at -14 degrees centigrades.
I drove for 1km without oil, then replace the broken hose and refill with new oil. Now only 1 and 2 works. It slip on 3rd and 4th. Due to the cold, I decided to go back home so I drove in 2nd gear for about 10km.
What do you think is cousing 3rd and 4th to slip?
What do you think should I test?