Fermentation stuck at 1020

Hi guys, 

I don't know what I had in my mind but I transfered my batch (after a week) to secondary without checking gravity. It was just full of foam and had an extremely vigorous fermentation so far so it just seemed ok. Stupid I know! 

So it's been 3 days at the secondary now and the gravity still at 1020 - when it should be at 1011, 1010..

My question is: Should I pitch a bit more yeast to get that gravity down? I really need this beer to be dry.

Thanks a lot for the help.

Some additional info: 

Yeast strain: 1272 - Harvested (3 beer)

OG: 1071

Days on primary: 7