
I'm not nearly as knowledgable generally as many members on here but can give you my experiences with my irish setter pup who is almost 4 months old.
We have had a couple of occasions where it looked like we were making progress and then had a setback BTW so I wouldn't worry too much about that,it seems to be just how it goes with puppies!!
My lad will go overnight and for reasonable periods when he's napping during the day without a wee,but when he's awake and active I would say 2 hours would be the usual period of time he would go without.He probably could last 3 hours if he hadn't been drinking loads and wasn't playing or getting excited but that would be the maximum I should think.
My problem is more that my lad won't ask to go out,or even make it obvious that he needs to go,so if I don't leave the door open or take him out at the right time he will just go on the floor wherever he happens to be at the time,so you're not alone with the surprise puddles on the floor!!
I find house training THE most annoying and horrible part of puppy owning without a doubt (well that and wet muddy paws in the winter but am trying not to think about that yet lol),I am too OCD about hygiene to cope with toileting on the floor of my home,but hey ho that's part of the package.I think it's easy to get caught up with the setbacks and forget the progress sometimes,as frustrating as house training is at the time,in a few months it will hopefully all be a distant memory and will wonder what we got so uptight about.
Hang in there sounds like you and your pup are doing fine,and sure it will all come together soon enough.