Kieran, the maximum file size is 125 kilobytes, not 125 pixels - the restriction is to the size of the file itself, not the dimensions of the image on the screen. 500 x 500-ish pixels should be fine, but you might have to compress it a bit (save at 80%-ish quality or so - depends on the original photo file size). Does that help?
You'll need to fix all the photos you've posted, as they're all too small to see the detail.