I'm assuming this kit was based on LME/DME.
If you had to top off with water after the boil, then the hydrometer reading may be significantly off due to the difficulty in getting wort and water to completely mix.
The steeping grains really don't add much in the way of fermentables to the mix. They do add color, flavor, aroma, etc. When I was using extract, I found that the steeping grain added no sugar to the mix.