How big is the pic? Reduce photo size to 800x600 pixels or less and see what happens. If that doesn't do it, look for freeware that allows you to "Save For Web" to reduce file size further.
You can go back and resize all your photos and re-upload them. That may get you room for more photos. You could subscribe to ICMag and get more.
Irfanview is a great little free program for doing basic pic edits like cropping and re-sizing. Jstrip is great for quickly removing exim data from a folder full of files.
Gimp is definitely an awesomely free image editor. I used it for years.