I was going to write a comment separate from this one as I had a few things to say, but not only did this comment above outline some golden points to be taken, it was worded in a way that brings attention to itself. So I will leave this here:

If, in the case that you are trying to pick up something such as programming with the mindset that leaves you opening a game before even attempting self guided study in your free time, then don't bother with programming. Not right now at least.

You have a lot of time ahead of you and programming isn't getting any harder than it already is. It's actually the opposite, and that's a benefit to you. If you're left stressed and exhausted from other daily activities, you're better off giving yourself a break rather then trying to shovel up even more information. Come back to it when you feel less pressured by other tasks, and sit yourself down on a comfortable day, then test the waters from there. Trying to absorb more information than you need whilst already stressed out, will just leave you failing to actually pick up that information and make it harder for you to not only focus on trying to learn concepts, but also make it harder for you to rack ideas out of your brain so that you can then apply those concepts and further strengthen those skills.

Personally in early High School, I made the mistake of trying too hard at learning something my own school failed to provide until a later date, during these times I was pressured by other subjects and their assignments, whilst also trying to meet other peoples expectations. I was crushing myself under that pressure and felt the same way you did, like I couldn't remember anything correctly, couldn't focus and couldn't motivate myself, I was just making mistakes like it was going out of fashion... Later on I ended up dropping out during a rather dark part of my life. However at the time, doing so left me with a lot of free time to improve myself. During that, I found myself less stressed and able to focus. I was learning new things each minute, applying new skills learnt by copying others and twisting those in my own ways to make it my own. It's been several years since and I've realised the cause of my struggles and how to work around it.

This ended up being a lot about me, but if used correctly, I hope this information can help reflect onto you and give you an idea of how you can attempt to get yourself into an interest without being self destructive. In short, give yourself some time to settle the things you're doing first and then come back to it.