There are a bazillion posts about this right here on this forum. If you want my opinion there is nothing you can do but wait and hope. If players can join then the server should appear on the list eventually.

Ok thanks for your help. So it turns out I had the correct port forward settings all along. It seems because of only 5000 servers being listed at a time is the reason my server isn't showing up. It's been 4 days now and no sign of it in the list. I'm not liking my chances and realised theres probably no point running a server if theres not going to be any players lol.
But thank you for all your help.
Muchly appreciated :)