It will be the size of the photos, not all photos are the same size, it's dependant on the complexity of the image, the lighting, focus and a number of other factors. It can literally double the size of an image.
As I've said before I hate it when people use 3rd party image hosting services like Photobucket etc, this has the potential to ruin a good thread. A lot of these companies regularly purge old or unviewed images from their servers, this turns a good post in to a train wreck. While I appreciate that it's not always easy for everyone to reduce the size of their images, there are a number of free apps that will do this for you on both Apple and Android (as well as PC's) systems. They are getting easier and easier to use, just reduce the image down to under 2048KB / 2MB etc and it'll be good.
It's not just the size issue, seems uploading from iPhone and iPads have issues too.
Tiger if you have any issues using Apple devices just upload the pics to a computer and attach them from there, that's what I've had to do the last few months