I suck at data structures and algorithm, how can i be good at it? Or maybe i suck at programming in general, i don't know, 2 companies emailed me that I didn't pass their technical exam, I'm disappointed and thinking maybe software development is not for me.

Persistence my friend, dont get yourself discouraged

First: Learn the basics so you have some basics. (I think you already have)
Then try to find companies that have trainee programs for developers. These are the one who are more willing to invest in their employees.
Try to get People around you (local comunities, Hacker Space e.g.) where you can get knowlede of everyday developer problems and how to solve them.
And the last and most relevant: try to find some companies where these technical tests are not relevant. These companies look for creative motivated and great developers which get their tasks done.

My company hired about 10 new developers im. The last 9 month. We have hired great people. Some of them would not have passed some technical tests but they are great at solving tasks and its fun working in this Team.

You have to know how which data structures behave and when to use what. Same for sorting algorithms.

Out of my head, I could do a Bubblesort, but not much else. I certainly couldn't write a red black tree without research, but I like green ones better anyway.