Is there a place to set the number of related products per row, like is done in the category page? For some reason I am left with rows that have empty spaces. Any suggestions?
https://www.teapartyribbons.com/newsite/index.php/satin/solids2012-09-08-05-09-55796622786/offray-single-face-solid/343-tornado-blue2012-09-10-05-37-33822330781-ribbon
I had a quick play with it for you, it seems like a CSS problem.
Go to row 504 of your style.css ".product-related-products .product-field" and try changing "min-Height" to 160px seems to cure it.