Heavily armed,
I think you already know the answer to your question.
Being only 5'6" with low metabolism, you are going to have to cut your caloric intake in order to get a low body fat percentage.
Unfortunately beer is very calorie compact, even light beer is around 200 calories a can. If you multiply 200 X 6 beers = 1200 calories!!! Most people need to be under 2500 calories a day, that leaves you only 1300 calories of food for the whole day.
If you want to get lean, my advice is figure out your daily caloric intake needs(there are formulas all over the net) And then stay at or under it. Also, if you have not already,drop the potato chips, cheeseburgers, and ice cream in exchange for baked chips, chicken breast, and frozen yogurt.
I would wager that you would lose the desired body fat if you would just drop the beer on the weekends. Or, you can cut your caloric intake during the week and splurge a little on the weekends.
Also, without being able to work out your legs it is going to be very hard to keep a good balance.
As far as hitting "The Plateau", just vary your routine, go from say bench press with a barbell to benchpressing with dumbbells, basically change your method of working out your muscle groups.
And remember creatine is notorious for dehydrating you, drink at least a gallon of water a day while your taking creatine.