peat moss lowers your ph, it's acidic, so adding peat should help, what was the ph for the store-peat? (should have been damn near 4.5)i'm not too sure about adding a soil that is that acidic, maybe for growing some tasty blueberries or cranberries... but I wouldn't for herb.
not unless you add a small amount, but that's just me, remember most soils will get more acidic over time.
I stand by my original advice, add some peat and some aeration, and some uncharged charcoal, and cook the soil for at least a month, maybe more considering it's getting cold now.
And holy crap, how is your soil's ph above 10?? That's gonna be a freakin chemistry class on it's own just to get it back down to 7