I'm new at formulating recipes but I think you will need more extract to get anything close to an oktoberfest beer at least at 5 gals. I did a very light lager that used 6 lbs DME. I wouldn't steep more than 1lb of the malt. I am assuming of course that you are doing an extract brew with steeping grains.
You might want to check out this site http://hbd.org/recipator/
, it has a free recipe building program you can plug your ingredients into to give you final SG etc.