Skeeter Pee low ABV

[Berry Juice]

I've made my first batch of SP.
I understand it's suppose to be low ABV.
Starting SG 1.090
Ending .999
Which should put it almost 12%
Last night, I polished off a quart and had no buzz feeling effect.
Felt like it was just lemonaid......
I was wondering if I added a little vodka to it to bump up the % a couple of points.
Question is, How much vodka to add to 5.5 gal batch to get it to 13-14%?

 

[sour_grapes]

Google "Pearson square" or use FermCalc.