Blackberry brew advice, bottling this Sunday.

I brewed a Raspberry beer, that turned into a BlackBerry beer because I couldn't find any decent raspberries. Anyhow, I think it fermented a little dry and tart, what would be the best way to sweeten it up a bit?

Lactose at bottling?

And if I do sweeten it, will that affect carbonation or the amount of priming sugar to use?

here is the recipe:

Type: Extract
Batch Size: 5.00 gal
Boil Size: 3.50
Boil Time: 60 min

Amount Item Type % or IBU
6.00 lb Extra Light Dry Extract
0.75 lb Carapils
1.00 oz Liberty [4.00%] (45 min)
0.50 oz Liberty [4.00%] (15 min)
1.00 lb Candi Sugar, Clear (0.5 SRM) Sugar 10.53 %
1 Pkgs California Ale (White Labs #WLP001) [Starter 1000 ml] Yeast-Ale

Est Original Gravity: 1.058 SG
Est Final Gravity: 1.013 SG
Estimated Alcohol by Vol: 6.11 %
Bitterness: 21.4 IBU

I added about 3.5 lbs of Blackberries to the secondary, racked ontop and left it for about 12 days. I racked to tertiary this past Sunday and will hopefully bottle this coming Sunday.

I want a higher than normal carb for this brew to help bring out the Balckberry flavor on the tounge.

Any advice?

Lactose doesn't ferment .so it would have no effect on the bottling sugar amount.