Cocoa and Chocolate Contribute to OG/FG?

I'm fermenting a double chocolate stout at the moment. I took a hydrometer reading after one week after fermentation and my SG was at 1.020, which is significantly higher than what I was expecting, but I'm not super surprised by the reading due to the following reasons:

1. I've been having mash temp. problems for a lot of my batches; usually they are too low. For this batch my mash temp. actually kept and my mash was around 155F; I wanted it around 150F.
2. I added 1# of dextrine to create some more head retention.
3. I added 6 ounces of chocolate and cocoa powder (2 oz. cocoa, 6 oz. bittersweet Baker's).

Even with reasons #1 and #2 I would have expected my SG to be a little lower. I had a grain bill of about 12 pounds (9# US 2-Row) and pitched two packages of Nottingham yeast and fermented between 62 to 65 degrees.

I did some research and couldn't find any adequate results on how much chocolate and cocoa powder will contribute to the OG/FG of the stout. Should I expect higher FG readings because of the addition of the chocolate and cocoa powder?

Thanks!

If there's sugar in something it's going to add to the og.

Update: Now that I think of it I'm pretty sure I used unsweetened Baker's chocolate, which to Revvy's response, would mean that there would be little-to-no sugar added. This might be a matter of mash temperature or grain bill that could cause this.
Grain Bill
9# - US 2-Row
1# - Crystal 90L
1# - Dextrine
1/2# - Roasted
Mash temp: 155f
2 x Nottingham Packages; Ferm temp 62 to 65f.
OG 1.060
SG 1.020

Should I assume the SG is correct or has fermentation stopped early?

Bring that fermenter to low 70's and give it a swirl to stir up the yeast. I think there is more fermenting to be done.