Not all blog posts displaying (custom theme)

Hi,

I’ve just set up a website for my partner, she’s a musician and wanted to move over from wordpress.com to .org and we’ve set it all up fine and put a purchased theme over the top of it.

The stumbling block we’ve got is the site isn’t showing all her blog posts in her blog section correctly.

This first happened when I did the blog import (had to use a plugin as the official importer didn’t seem to work for us), when I brought in all the posts without any media it displayed them fine, every single post all on one page. When I added all the media, that’s when it went wrong and only displayed the first 6 posts. I tried changing categories and renaming them, it wasn’t the category of the posts that was the problem, it seemed to be the amount of media. My workaround for this was to delete every post, reimport them and only add the media for the previous 18 months, this seemed to work fine.

She’s put up a few new posts and we’ve noticed it’s happening again. I’m considering having the blog section just be the last dozen posts or so, with the sidebar having the archive that can be selected, but that’s not ideal as she’d prefer them all on one page and obviously I don’t want to have to delete everything and reimport all the time if it keep happening, so I’m hoping someone can suggest what might be going on and offer advice for how to fix it!

The address for her website is catherineelms.co.uk
Link to the blog is in the main menu at the top or you can just click here: http://catherineelms.co.uk/?cat=140

I appreciate any and all help people can offer,
Daf (also this is my first time here so I’m sorry if I’ve put this post in the wrong place)