Yes, you missed your chance to get an accurate ABV, but you can always guesstimate. Fruit is hard, because even if you did take a gravity reading, the fruit is solid, so there is no homogenous mixture in the beer. I plugged in 6 lbs of apricot puree (assuming you would lose 2/3 weight by drying them) and 8 oz of turbinato sugar into Beer Calculus and came up with 1.018, so it would add .018 points to your OG. We can extrapolate 3 cups of Riesling at 11%, diluted to 5 gallons (80 cups) would net you a .4% increase in ABV. 3/80*11 = .4125. So, I think if you raise your OG by .018, and calcuate ABV normally, then add .4 to that, you should have a decent estimate. So, by my calculations, I think you are right about 8% ABV.