If anyone runs into this wondering the same thing, I got this working using this code:
<?php global $current_user; get_currentuserinfo(); $uid = bbp_get_current_user_id(); ?>
<?php if ( bbp_get_user_topic_subscriptions( $uid ) ) : ?>
<?php bbp_get_template_part( 'pagination', 'topics' ); ?>
<?php bbp_get_template_part( 'loop', 'topics' ); ?>
<?php bbp_get_template_part( 'pagination', 'topics' ); ?>
<?php else : ?>
<p><?php _e( 'You are not currently subscribed to any topics.', 'bbpress' ); ?></p>
<?php endif; ?>
Basically you just have to specify the current user’s ID number in the bbp_get_user_topic_subscriptions function. I’m running into another weird problem that I haven’t been able to fix though: If this is in your sidebar and you view a single forum, it will only display the subscribed topics within that forum.
Hope this helps someone.