Getting an adult theme is not a face-life, its a half measure. It’s attempting to squeeze your vision into a pre-designed system.
As for platform, well dump Joomla as soon as you can. It’s time came, and went.
Switch to wordpress.
Don’t buy a theme, get one custom designed. You can do it yourself pretty easily. If not, it won’t cost you must to get exactly what you want. There are more wordpress developers/designers globally than for any other platform out there. I have been working with wordpress now for nearly 10 years, and there is no Joomla, Drupal.. ect, website I cannot develop better on WordPress.
I’m sure there are a good few wordpress experts on this forum to be honest.