I would focus more on basic technique and less on science. You don't have to be completely on top of every detail to make beer. You are apparently building up a wealth of knowledge which may be distracting you from fundamentals.
I think you should do what I used to do for lab classes. Write out a numbered list of brewing steps, check it, and follow it.
Personally, I would keep this beer if I had room for it AND I liked it. Otherwise I would dump it. It looks pretty far from Guinness, and there are plenty of good stout recipes you could replace it with.
I wonder if you are confusing draft Guinness with bottled Extra Stout, which is heavier and gassed with CO2. Draught Guinness is a light beer which is low in alcohol, and it's dispensed with beer gas. The draught has an FG of about 1.011.
You will definitely want beer gas and a special faucet if you want the real, creamy draught stout experience. Can't get it with CO2. There is a way to fake it with a syringe.
Kegging is expensive at first, but it's much better than bottling, which requires much more work and may put beer on your ceiling.
You just need a 5-pound tank, a regulator, and a stout faucet.