Hello,
What license and version of phpdocx are you using? Your username doesn't have any license tied, please send to contact[at]phpdocx.com the username or email of the phpdocx account that purchased the license you are using.
There's no method to get the height or width of text content, but phpdocx includes options (keepLines and keepNext) to keep contents on the same page (paragraphs, lists, tables, HTML...); these options can be applied to new contents, WordFragments, templates...
If you are using a license that includes technical support, we can generate a custom sample script. Please note that the trial package doesn't include this kind of support.
Regards.