To fix the problem I was having I decided to use my beloved Picmonkey and create custom covers. I loaded up my famous dark denim background and cropped it... This I had to look up though, because I tried several different image sizes to see how they would load on my Pinterest board for the cover and most of them didn't work. A quick Google search landed me at web.search.social where I was able to find the exact size of the 'cover photo image' for Pinterest: 222x150. And I started making covers:
What do you think about the end result compared to the before?