Hi, I'm glad I saw your post.
I nearly got expelled from high school and ended up dropping out. When I went to college, I had no idea how to study, and I spent so much time writing code for my own private projects that I had almost no time left over to study or do homework, so my grades were awful.
But I kept getting stronger at solving computer problems. Employers asked me lots of questions about Linux, and C, and how I'd solve various problems, and so on. But nobody has ever asked me about my grades, or my GPA, or the courses, or my degree. I know grades and degrees may seem important to you now, but in my experience, it just hasn't made any difference. What has made a difference is the huge amount of time and effort I've put into programming and solving problems.
I'm 35. I work at a startup. I work very hard, but I do whatever I want. I'm still learning and getting better. I don't have a boss. I work with my friends. One friend, like me, had disastrous grades. Another friend, probably the most brilliant and talented person I know, did not finish college.
You simply don't need permission from a university to be what you want. And the university doesn't even have the power to grant anything except a certificate. If you want to become a software engineer, you do it by putting in time every day. Always curiously searching and probing and testing and challenging yourself and making yourself stronger.
Like I said, I know grades seem important to you now, but your dream is not destroyed -- it's hardly even started. Go find an interesting repo on Github and study the code and make a meaningful contribution. Solve a tricky problem and write an article about it (explaining to others is an excellent way to solidify your own understanding).
Don't get discouraged and don't ask people for permission to do what you want! :) Good luck.