I know how you feel. I started my first semester at Uni last semester (I’m a transfer so it was junior level classes). Long story short: I was already depressed and stressed out going in (unrelated to academics), was unprepared for the rigors of Uni, worked really hard for crappy grades and altogether almost cracked and lost it. Never felt like that before, it sucked.
Try changing your mentality of the material and how it’s covered. You may not agree with how the professors teach or what they expect (I’ve been there), but the fact of the matter is you can’t change that so the only thing you can do is adapt. Don’t fight the current, go with the flow. In the end it will make you a better, more knowledgeable student; theory provides the basis for application.
Are you having trouble with the content of your classes or just the workload? Either way, try better time management. I know that sounds like an obvious idea that’s been engrained into our minds since childhood, but you’ll be surprised at the outcome when you actually practice it. Plan out your week beforehand, designated times to work on your classes, start homework right away, etc. Try to stay ahead.
As the other poster said, try taking less classes. It should be early enough that there won’t be any drawbacks for withdrawing from a class, but it depends on your school. Talk to an adviser about it.
One thing I did last semester that really helped (and this is probably the most important): give yourself designated time to relax. 1-2 nights a week, play some video games, watch some movies, read stuff you enjoy, whatever your muse is (but don’t do anything too destructive). Allow yourself to feel human again and enjoy yourself a bit. It’ll definitely take some of the weight off; you’ll be less stressed and be able to focus better when it’s time to hit the books.
Why did you choose engineering in the first place? Try to rekindle that feeling and get excited about it again.
Acquaint yourself with resources to make your study sessions more productive. Use online resources like youtube, khanacademy (you’re probably past the point of its usefulness but there still might be something to help), MTI opencourseware, do a google search for video lecture on the given topic. Get yourself solutions manuals so you’ll have something to help you when you get stuck on a problem. Buy some Schaum’s books. Start or join study groups. Streamline your study sessions.
Keep in mind, junior year is notorious for being the heaviest year for engineering. Once you make it through this you’ll be on the home stretch.
Things will get better, I wish you the best of luck.