On your own ID (in the upper left of one of your posts, for instance) you can click and choose "Find Member's Topics" and the results of that will show you all the threads you've started. If you choose "Find member's Posts" it will also find all the threads you've commented inside, regardless of whether you started the thread.
You can also do an advanced search and select an exact ID as one of the parameters for the search. This can be useful if you only want to see your posts inside a particular subforum, as that can be specified too.
Hope this helps!
~~waterdrop~~