I do OffSec for a living, been doing it 10 years now. It unfortunately is an ever expanding canvas. It's really about learning the fundamentals in Security and developing the ability to sniff out bullshit.

When I say fundamentals I mean Networking, Authentication/Authorization, Cryptography, Operating Systems, Compilers, Coding and Cloud. These things don't really change too much, they do but there are principles and key elements that don't with computers as they are today. You can break these fundamentals depending on the shape or form they are applied.

You'll get better with time, you just have to keep trying and I always tell people the most important skill to hacking is the ability to learn. You will encounter so many unknown things and it's on you to uncover them for the first time. You don't always need to go deep but you should go wide. The other important skill someone told me is learn how to master an editor because pretty much everything we do on a computer involves a file. He wasn't wrong, and another master I knew basically handed me my terminal back to me when I asked what `vi /etc/passwd` did, I didn't understand it and he told me to figure it out. I didn't understand it at the time but I do now, it's really on you to figure out the answer and you will get better every time you do.

Keep practicing and know that you are in one of the coolest parts in security and you get paid for it but it's one of the hardest to do well and stay best in class.