Hiya,
I’m assuming that you were using the the automated method of displaying subheadings? If this is the case, the plugin uses the ‘the_content’ filter to prepend the subtitle before the content of the post (or page) with the tags defined on the settings page.
The only way to ensure that the subheadings appear exactly where (and how) you would like is to edit the theme template and call ‘the_subheading’ function from there:
<?php if (function_exists('the_subheading')) { the_subheading('<p>', '</p>'); } ?>
You should then disable the auto append option on the settings page.
Regarding the ‘big gap’, this was probably a result of the tags used to surround the subheading. Altering the tag or adding additional styles could have resolved this layout issue.
Does this point you in the right direction?