There's a lot of forums which some may find a little daunting. You could consider hiding some until you get a handful or more specific conversations that require a separate forum, or you could try out fluid view which removes the complexity a little and focuses on the discussions themselves. When you start growing beyond this stream view, then you can switch back to more organised categories and forums.
You've done a good job of seeding the forum, but I'd love to see a mission statement at the top, or some onboarding block that explains the benefits of signing up.
Also, produce some content around the forum to get people visiting. Writing blogs and articles that you share over your social media channels are a simple way to entice new visitors in. If you're not an expert writer, then why not just create a blog that takes 3-4 articles from around the web and add a little commentary to them as a 'round up' blog.
Perhaps writing an anonymous blog with personal experience will help new members feel comfortable enough to share.
Remind people that they can sign up with a username, which, unlike social media, means you can remain anonymous to a degree. Push the privacy angle as this is a good benefit over social media.
I closed my Mental Illness forum because it was causing me to be really depressed. So I made a new website and it's about Going Cord-Free and ditching your cable bill and you can view it here. Go Cord-Free
TOO much text!. You can cut 90% of it and express the same message
"Thanks for visiting WeLovetheEighties.com! I'm guessing that just like us you're a fan of the eighties! The eighties decade produced some of the best fashion, music, television shows, movies, toys and video games which people talk about till this day. Since you're already here have a look around our community and join in on the discussions! It only takes a few seconds to sign up. Click on the sign up button below and you're in! Here at WeLovetheEighties.com you'll find that you're amongst cool, fun and friendly like minded eighties lovers. By joining our community you'll get to enjoy and reminisce with us! Besides participating in our discussions you'll be able to create your own club on whatever you want or join an existing one. You'll also have the ability to start your own blog, start your own image gallery, customized profile and even write your own articles and share them with us for everyone to read! So get started by clicking on the sign up button below!
Would like to write and share an article on the eighties? Let us know by contacting us! We're looking for some awesome creative article writers!"