I'm sorry you've been so frustrated.
The Tapas Forums are separate from the main site, in order to see the threads you've posted on the forums, once you're logged in to the forum, simply click on your profile picture in the upper right corner and then mousewheel-click on your name. That will take you to your forum profile page, where you can see all the threads you've participated in on these forums. That should help you locate this (or any other thread you've joined) anytime you like in the future.
I haven't experienced the loading issues you are, so the issue is likely between you and your ISP. Are you on a mobile device with a poor connection? I find using a desktop for preparing and posting my chapters to be intuitive and straightforward.