I personally started using the 18+ tag in my RPs for the presence of darker themes and gore, but I keep almost exclusively to Casual group RPs. Pretty much agree with Pugbutter, too.

I’d have to agree with Haley too, most 1x1s consist of potential smut in every conceivable romance plot. So, if you’re up for it, I’d definitely browse through Free or Casual (some Free RPs run almost exactly like in Casual, so it’s all about preference).

And to add my own two cents: you’re not alone in feeling overlooked, like your threads don’t exist or people just don’t show up or show any interest. I’ve been there, many times. I’ve had a few threads gather interest just to die off in a few weeks because over half of the people either don’t come in from the interest check or literally just don’t log in again for months. 
Now, I’m not exactly a confident GM, so maybe that has something to do with it. Maybe it shows. In your case, it could be the age of your account. Who really knows...