24 hour urine test..

So I have to do a 24 hour urine test to test protein in my urine. They gave me a huge red jug.. my problem is even tho I’m pregnant & stay hydrated I barely have to pee.. there’s barely any in the jug.. I mean I still have a little over 12 hours but granted I’m going to bed soon.. is there like a minimum amount or urine the lab needs??