Hi, I worked in the game industry for a while. I worked on AAA titles, indie stuff and semi-indie. I'm not a designer though.

I would say that the best way to become who you want to be is to make many of your own excellent SMALL indie stuff and work your way up from there. Fortunately you're in the right double major! Build your own games, from scratch, over and over again until you produce something really good. Make little 24 or 48-hour games for hackathons, ludum dare, global game jam, etc. I can't give you better advice than to simply scale down your ambitions a lot. If you've never finished anything then that's your major problem and you desperately need to leverage some success spirals before you can dive into a bigger idea.

If you have a giant idea that you want to implement but it's too big, bite off a tiny chunk. Maybe it's a gameplay mechanic, maybe an art style. If you demonstrate a kernel of something that seems good, then you will be encouraged spend more time improving it. I think there are good subreddits for indie games where you can get feedback online.

Another way that an artist friend got into the industry was by taking a QA job at an AAA studio. Then he spent a ton of time outside work learning the tools that the artists used, playing around and making cool levels and showing off his skills. He made friends in the art department and showed them his stuff, and when he finally made something impressive, the art people showed it to their bosses and he got promoted to an art position. This strategy requires substantial willingness to grind, both as a QA person (the job is ridiculously boring and requires long hours) plus the outside-work time.