I'd love to hear feedback and suggestions as to were to go after completion. C++? Python? Java? Other C courses?
Learn some data structures, for sure. Linked lists, trees, maps. Those will take you far, in any language. With C you'll know them at a primitive level.
You should go write a bunch of C programs next, that's what you should do.
I can't speak to the classes, but you can't learn C, or any language really, in 7 classes.
You need to apply the language to things that interest you and get things done, and it's best done without a safety net.
You need to go and write a bunch of stuff that maybe in the end you're not happy with so that you can improve later. It software, you can change it.
Simply, it takes practice, a lot of practice, to learn these environments and be productive with them.
I also suggest to anyone learning a language, that while learning, you type in all of your code. Don't cut and paste it from the web, type it in. If practical, don't download it from the web, but type it in. Your brain processes it much differently character by character than just drag and dropping large blocks of code that you know nothing about.
Typing it in lets you asses what you're typing. Determine "Oh I see what they're doing here" vs "WTH is going on here?". You also have a better chance when you're in some section of "I don't know" to have it make sense later when the rest of the code is in place. When the "Aha" hits.
There is a LOT of code in the world and on the internet, but there's still a lot of room to find your own voice, write your own code, make your own mistakes, and fix them. There's a bunch of alternatives out there, don't chase them. Best to work with C and find its warts and problems and such as they apply to you before you go run out trying to find solutions because of what someone else says.
I'm of the opinion that an expert in anything is not someone who knows something, it's someone who knows how to fix something. There's a zillion books on how to tile your bathroom, and almost none of them really help you when your floor isn't level, the wall is out of plumb, or something doesn't set right. To fix things, you have to break things, and to break things, you need to make things. So, go make some stuff, break it, fix it, and make it again.
It's always good to learn other languages, but it's better to be fluent in one before venturing out. Only then will you be able to better appreciate the new language, and, perhaps, the old one as well.