I would suggest that you experiment with it a little @Former-Member until you are happy with it. There is an option to edit your post above, so you can use that to delete the photo an repost it in another size. It takes time for the images to be approved the first time you post them. After that they are in an album under your profile, so effectively "pre-approved" and can show up faster in the thread.
I go into the photo in my phone and crop it that teeny bit before accessing it to upload through a forum thread. That's what works for me .....
