Where can I check my current image storage level?

This can be done by going to Images in the menu across the top of the page. Then select My Images. Click the Disk Usage button near the top right of your list of images to find your current image storage level.

Note that images that are in your Recycle Bin are counted toward your total storage. If you are sure you do not need those images, then you can click on the Recycle Bin tab and then the Empty Recycle Bin button to remove them permanently from your account and image storage level count.