Hi there,
First of all, to make things clear, I am NOT in posession of any flight license, so my advice here will not be related to what you do wrong in flying, more or less, about the mental stress and pressure that might influence you in your training "progression-wise", if I may put it that way.
I'll try to help out here, by sharing a personal story. I think this is the best way to show you that I may, or may not understand you. So here goes:
Back when I was in high school, I was about 15-16, the age is not what matters here. At 15, legally, you're allowed to work, thus, I got my first job. I was going to school full-time, and working 35 hours a week in a fast-food restraunt, pretty rough, yet somehow I thought that I would be able to do it.
So I continued this way for some time, until at some point, I was not able to manage school and work together, they're just not made for it when they're both full time. So, I had to set my priorities, re-establish my confidence, due to the fact that my scholastic performance had drastically gone down, not because I was stupid, or amazingly idiotic, yet I just didn't manage my time right, which of course resulted in a HUGE, and might I add, HUGE amount of stress over me, which not only a 16 year old kid should not have, but any human being shouldn't as well...
This kind of stress comes in and blocks your brain somehow, the school nurse explained it to me, yet I don't remember much out of it. It may also be chronic fatigue, yet I won't diagnose anything. If you're having difficulty completing your PPL, I suggest that you do listen to your instructor. Try to take a five days off, escape from reality, rent a lodge somewhere near a lost lake, stay in nature, get away from the city, that can hugely help with stress management. I also think that you might be stressed because you want to do too well. Although I haven't had any flight instruction, I know that when learning a subject, or new material be it applied or theoretic, questions are key. If you're shy or too proud to ask questions, then too bad for you! Smart people speak up and ask when they think something is wrong with them, or when they notice that they're skidding off that road that we call "understanding".....SPEAK UP, it's imperative that you do so!
Now, when I was stressed, a teacher suggested that I meet with the school psychologist to discuss my tiredness, my whole chronic fatigue, lack of concentration and constant stressed attitude. I met him, we talked about stress, made out a schedule to respect, and eversince then, my stress level has gone drastically low. Take note that being stressed, and I am not intending to stress you even more, yet stressing too much can make your health deteriorate, so I suggest you go out, do a sport, beat the stress out of you. Back to my story, due to the fact that I never was one of those popular kids in school, was always the type of kid that would hang out on the 3rd floor, eating with the math teacher while solving math problems, so then I could actually get to work 35 hours a week and make a rotten salary (7,60/h at that time). Mainly, to get to the point, I was taking bites bigger than I should have out of life. Meaning that I was uselessly rushing myself.
I had the same situation in Cegep, where I wanted to take more classes, take bigger gulps out of the material, get more credits. Again the academic advisor told me to take it slow, do things right. Because it is only when you rush that you actually screw things up.
What I think that you should do here my friend, is that you sit down, and write everything down. Take a piece of paper, and put all your thoughts on to it. Then, carefully enumerate a priority list, making sure that you make those choices carefully. According to that priority list, you should have 12 hours per day out of 24 to respond to those priorities, thus keeping 8 hours for your healthy sleep (very important might I add), and of course the 4 remaining hours are to be contributed to your daily transportation, food, and a bit of leisure.
Once you'll have organized yourself, set your priorities, you'll feel a lot more set on your goals. Try the same system that we humans use with dogs. Reward yourself for Christ's sake! After you've respected all that you've had to do in your day, you may even end up with extra time on your hands. Now, I don't want to write a book on how to organize your time or set your goals in life, I am far from having lived even the first half of my life (hopefully

), yet I really hope that your situation works out.
If there is anything else I could do for you, any kind of advice, please feel free to PM me.
My two cents...
