掲示板 Forums - See my own posts

Is there a way to find my own comments I've made in the past?

Open "My Writing" and look under "My comments". If you meant on the Forums, I don't think you can.

Edit: I guess you can add the "Latest forum posts" widget to your dashboard and check your "Subscribed Topics". That's usually also where you've left posts.

Just keep in mind searching for yourself only finds posts that mention your name, not your posts. If you (OP) look up your name right now, you won't find anything :)