Have you tried using the "User CP"?
It stands for user control panel.
If someone posts on one of your threads, it will appear here.
Also, if you post on someone else's thread, and someone replies, it will also appear here. For as long as those threads are active, wether it is yours, or someone else's that you have replied to, any activity will make those threads appear in your "User CP". If for some reason, there is a thread that you do not wish to be bothered with any more, you need to unsubscribe from it. But you automatically get subscribed by posting. It is for me anyways, so there may be a setting for this to happen. It works great because it makes it super easy to find all your replies, and keep up with the activity on threads you have posted in, all in one place.
Hope this helps,
evo