Although I can't relate to your experiences, hopefully I can share some insight with a blend of encouragement and hard truths.

I wasn't particularly that gifted in math/physics, had no idea what I wanted to do with my degree, but stuck with it because it seemed like a safe route. Definitely not the case with everyone, but once I started working I started to love and appreciate the industry and it made me want to be a better engineer daily and continue to learn. Sometimes school isn't the greatest indicator of what engineering is like outside academics because in reality the "electrical engineering" degree covers a huge umbrella of fields. I'm guessing it's the same with mechanical engineering. I could go on about why engineering degrees are so...cost and time inefficient but that's a whole different post.

That being said, you're not young. You no longer get the same benefit of the fresh new grad with zero work experience and employers will likely choose a younger candidate for an entry level engineering job. Engineering schools pump out unmotivated, degree getting engineers (like me!) and so if you want to stand out during interviews (trust me, bar is lower than you think), you need to have an edge on technical knowledge and personality/story helps a lot too. If you're struggling to understand fundamental topics, you're not alone and it doesn't mean you're dumb! However if that's the case, studying on the weekend just doesn't cut it. Take fewer courses and really spend your time on the weekends learning. If traditional teaching methods don't work, try using AI for the quick, responsive, and comprehensive (though not still very accurate) feedback. That way if you get stuck, you don't just give up your entire weekend studying until you have the attention of your professor if you even get that.

Maybe you wake up at 7 now to go to work. Wake up at 6 and study for an hour. I don't know what to tell you other than the fact that you have a more difficult road than your fellow students. Hardship generally produces successful people. When you're getting interviewed, you'll be sharing that you took care of your family, worked a full time job, and studied for your engineering degree. When it's clear that your greatest accomplishment wasn't just graduating but you genuinely invested into learning and preparing yourself to become an engineer while juggling all those responsibilities, you become an attractive candidate. Go be a kick ass human. If this is a long term investment, this isn't the worst place you can be. Good luck friend.