Seriously that's not surprising. Typically when I move my conical upstairs for bottling (I hate doing that w/5.5g or more in there, need my dedicated space done!) I will see a bubble, or more, And that's
2 weeks in the fermenter! I then will take a hydro reading, and will likely be at terminal (FG) gravity.
Also, go to Brewer's Friend, use their recipe calculator, entering in the fermentables (grains or extracts, its all there!), hops, yeast and other data as requested- should all be listed in your kit. Then BF will calculate the OG (original, post boil gravity, what goes into your fermenter) and will give you a FG as well. You can measure these as well with your newly shorter hydrometer that by now you've purchased!

Then compare. With an extract kit you'll likely be spot on. With AG, it will depend a lot on your system and methods, as well as your water. You can play around in there and see impacts on OG/FG (fermentables, yeast, mash temp etc..). But I'm getting a bit ahead of myself... I like brewing!
As for another resource, Palmer's book is available on line too.