Jessica, I found a solution in another thread that lets you set the number of columns used for displaying products. Go to your WP dashboard and then go to Appearance > Editor. Then open the functions.php file (it should be listed in the righthand sidebar) and paste this code in the section reserved for custom functions:
global $woocommerce_loop;
$woocommerce_loop['columns'] = 3;
Then you can change the number to whatever number of columns you want. It worked for me and I hope it will work for you!