Do you have access to your router/a computer at home where you could run monitoring software? I don't have experience with the PS4 version, and I can't be sure that the amount of bandwidth used would be the same as on a PC. If you have router access, that's the easiest place to start logging the amount of data used.
If so, what router do you have?
If not, what kind of computer do you have that you might be able to install monitoring tools on?
Thanks for the response - I have both the PC and PS4 versions, I'm going to make a leap and assume that they take about the same amount of data.
Actually...if I'm using my phone as a hotspot, I believe there's a way to track that right on my phone. I'll give it a shot and report back...