Should I build my own CMS or should I modify one?

I'm not your typical coder. I was a Java developer for 3 years from 2004 to 2006 and stopped coding since then. I'm more of an entrepreneur and code occasionally when I need to build prototypes. Most of my past 2 years of coding have been modifying codes on WordPress themes and plugins. I know enough PHP, Javascript to understand what I'm reading and editing them (StackOverflow helped tremendously). I've never built a project from scratch using PHP/Javascript.

I wish to build a project that allows users (logged in or not) to post content (unique text and images that I can't reveal the context for now) on my site and me (admin) and my moderators would review and publish them.

To ensure the site is up-to-technological-date and fast, I thought of using Node.js. So, I was thinking of modifying Ghost CMS. Is that a good move?

Or should I hire a node.js coder but it's a non-profit project and I prefer to depend on myself than a paid coder (I only got $4k budget for this project) or volunteer (working/volunteering commitment and schedule may be an issue).

Any advice is appreciated.