Do I just chalk this up to being an inherent problem with having to stop flying for 3 months at a time, or was I facing a rather harsh examiner or is there a genuine problem with my school's approach? I could really use some advice.
It is certainly partly attributable to item one, lengthy periods away from flying. It could be the school's approach, though the training should be to a common standard. As for harsh examiner, that's not something you should focus on - the examiner with examine to the standard, and it is in your interest to be able to fly to the standard, after all, it is a minimum standard, and you want to be at least as good as the minimum standard as a pilot.
You are asking a lot of yourself with low experience to recall and put into practice skills which are three months old. That can be difficult for more experienced pilots, so don't feel bad about that, though that does not solve your problem either. I find that some new pilots struggle because they do not dedicate themselves to their training, it sounds like you struggle because you
cannot dedicate yourself to your training - for three months at a time.
My advice: Take the opportunity which life offers you to fly. If you cannot build skills, or reach the next stage, simply enjoy the flying. One day, with the pressure off, an instructor will tell you you're ready. I did my helicopter license this way, I just flew once a month for fun as I could afford it. After a few years, my instructor told me to take the flight test, I would pass easily, and I did. But I was not in it for the license, just for the fun. Yeah, it sounds cool to tell people that you have a PPL, but it's just a piece of paper - for now, don't focus on the paper, just the fun. If the school is dedicated to you, they should be telling you that you're not flying consistently enough, if they're telling you that, listen. If you cannot change that, it is what it is, you're the customer. Look forward to a time in your life when the training can be more consistent.
One day you'll have a license, and look back at this phase of your life as a set along the way. In the mean time, you're spending the money for the fun, not the license which is eluding you. Like many of us, you're lucky to be able to fly, focus on, and enjoy that!