Image size 150px – Solution?

I’ve seen so many people with this same problem.
Thumbnails are always cropped 150x150px. I can css enlarge it, but it only streches the photo.

http://www.altamiranyc.com

Any solutions?
Or should I just give up and try a different plugin like every body else did?

Thank you very much!

https://wordpress.org/plugins/simply-instagram/