A blue silver has a bluish tint to the coat - in the pictures she kinda looks that way. A true silver tabby is a stark contrast - black markings and a really silvery coat. I'm thinking she might not be a silver.
I only recently learned about blue-silvers. Will see if I can find a good picture of one.
Here's a description - see if your cat matches one or the other.
Blue Silver Tabby: The ground color should be pure, clear silver. Markings are deep blue, affording good contrast to the light ground color. Eye color green or hazel. Nose leather and paw pads rose. NOTE: The addition of this color to the standard would apply to all ‘pattern’ areas, such as the Mc Tabby, Patched Tabby, and Patched Mc Tabby.
Silver Tabby: The ground color, including lips and chin, pale pure silver. Markings dense black. Rims of eyes, nose and lips outlined in black. Eye color green. Nose leather brick red, paw pads black or charcoal.
Silver tabby picturehttp://www.alken-murray.com/DanceKing.html
Pictures are not the greatest but you can kinda compare them to your cat and let us know what you think