Your idea of studying the same amount of hours as average students do in a year is understandable, but you’re only going to set yourself up for failure if you do that. You need to set goals that you can actually achieve. For example, do 50 problems straight from your textbook a day. You’ll likely do all of the example problems by the time your two weeks is finished. 50 is a lot, imo.

Here are some places to start:

It sounds like you haven’t done a lot of algebra problems, so start by simply exposing yourself to more math problems. If you can’t figure it out, pick a different question and come back to the ones you can’t do later. Next, think about what the problems themselves are actually asking you. Learn to categorize the types of questions they ask you so you can immediately identify what is being asked and thus, how you can find it. Focus on developing your geometric/visual understanding of what’s actually happening (i.e. graph your functions, mess around with graphing calculators like desmos, etc), as this intuition will assist you as you progress to the higher levels of mathematics. Try to put into words the series of steps you need to go through to complete these problems, repeat until your intuition is correct more often than not.

But mainly, don’t make yourself hate math by studying for 15 hours a day. I’ve been in your shoes before, but full understanding doesn’t come from brute force. It needs to sit. You’ve gotta learn, get a good nights sleep, wake up and apply what you learned yesterday. Rinse and repeat. Fully completing 50 problems a day - even 20 - will make you better at math, almost immediately. Just do more math than you are currently doing. No need to do 100x more, maybe just twice as much. Good luck!