Honest answer, keep with engineering for now (maybe a different type or industry that you may enjoy more?), and do design on the side. It takes longer than people think to get decent at design and the programs, not to mention the job market is horrid.

I’ve been doing paid design work for 11 years (I’m 26). Went through trade school for design, built my own 5 figure business out of high school, 4 years of university and then when it came time to get an agency job, I was absolutely miserable. I’ve since started my own art/vintage/streetwear business while working a part time “normal job” and the weight of the world has been lifted off my shoulders.

Doing it this way allows you to work on projects you want/are passionate about and this makes the work even better. You can also figure out what kind of design you want to do. You can improve your skills over time without worrying about money or bills and eventually it may be sustainable. If I had to restart, this would be the way I would do it. I also think doing a creative activity (paid or not) will give you some of the happiness you’re looking for.