Image On Facebook Changes

I was wondering if anyone could help. Sometimes when I post my image on Facebook it has to squares image is next to text. The image is very small. Other times I upload the image is on the top and writing is below the image is much bigger. I thought I have uploaded them all the same way by going to my fine art page opening the image I want to post then copy the url on top. I also tried it with the url on the bottom corner. I would like them to be larger so they can be seen and not overlooked. I have noticed a huge difference on the size being larger. Thank you so much for your help. I will include the facebook page I am uploading to just in case I did not make sense. Laura

https://www.facebook.com/lauraduhaimephotography