Spoke to the woman at the Hydro dam wall as well, a few times. I know there are two firefly markings on the walls at the university and tried both conversations and still 36/37, did the first conversation after the prologue before you attempt to go to the gate. I even did the optional conversations with bill and the note his partner left behind. When he reads it, and after he tears it up, spoke to Ellie in the car and did the one at the dart board 36/37. I watched a video on all the conversations and recall every single one since I have played the story 3 times now :/ when I have time on my off days I will run through chapter select and try and see if I missed any.
If that does not work then I will complete it in Survivor+ and then delete everything including updates and run through it on easy and take note of all the conversations I have had by checking the counter hopefully that will give me better results.
Other than that I am progressing quite quickly with Wolfensteins's trophies, just have to play as normal and they pop. Looking forward to get Infamous: FL's and got my eye on a copy of Sleeping Dog's or Diabolic 3: UED but I already have it on PC so I may just give it a skip (despite it being an easy platinum)





