Either one of two things.

You have it set to a lower resolution adn are mistaken the compression value for the resolution value setting on your camera.

OR, what I think is the cause:

You are looking at the file size, around 5.5 MegaBytes, 5.5MB, which is about a typical file size for a low compression 10 megapixel image.

To find out the resolution of an image, there are a set of numbers provided, like, 4272x2848. Those are the number of vertical by horizontal lines, multiply them and you will find out your resolution or "Megapixels" 4272*2848= 12,166,656. So, 12 million pixels. The data size can also vary depending on the tonal content of the image. Images with a lot of sharp detail will typically run higher, images with smoother detail will run smaller.