So you added the sugar to back sweeten it or when you were mixing the must up to ferment? I am confused here. If you were adding sugar to back sweeten you do that to taste. You boil 4 parts sugar in one part water to create a syrup and add a bit at a time sampling until it suits your taste. Hopefully you stabilized the wine first with sorbate to prevent a renewed fermentation if you were indeed sweetening the wine. If you were mixing up the must for fermentation you add sugar until you reach your target SG for the end alcohol content you want, normally around 1.090 for a starting SG.
ok the black berry was done I stabilized it. After took 4 lbs of sugar and boiled it in water added it to the black berry a little at a time until it tasted sweet enough. It took 4 lbs to taste as sweet as I think I like. I am just a little concerned about 6 months from now what it will taste like.
Ahhhh, OK, I understand now. Well, in my experience I have always thought that the wine tastes a little sweeter down the line but not too much. I normally stay just a bit on the tart side but then again I do not like sweet wines but do sweeten fruit wines, particularly for the wife. If it suits you now and you like sweet wines, you ought to be OK.