Masonry not working – blank space between featured image grid

I have been trolling the internet and trying everything I could find for days, and I am desperate.

I am new to wordpress, so I will try my best to make my problem as clear as possible.

My website is http://www.livinginretrospect.com

I have my homepage set to display recent posts, but the featured images do not show up in masonry format. Instead, the lefthand column’s image automatically aligns with the middle column’s image (the right column is my sidebar). This is fine if both images are the same size, but if the middle column has a larger picture, then the left column’s picture auto-aligns to the picture below leaving a huge white space for no apparent reason. I have tried numerous random .css additions that I found on various websites, but none of them have worked. I have deleted all of the .css that I have added previously.

I do not have very many plugins, and I have only installed plugins that had very good reviews and a lot of users. I have seen other sites that have the masonry feature working just fine. Am I missing something in the settings or is there an extra step that I need to go through?

Thank you so much for your help!

Bobbie