Ok first time making wine, had a bunch of grapes left over from our vines and after 65 jars of grape jelly, I decided to use what was left to make some wine. So I've had help from a friend and he's got me on the right path.I added yeast Fermentation when well, 1st racking and 2nd complete. I'm at around 10-12% alcohol. I tasted it the last time I racked and it had a little bitterness. What and when should I do it add? Wanting it to be a sweet wine not dry, so will probably add sweetener. I'm unsure of when I should do this and worried that if I add it too soon it will re ferment. Started this batch in early August this year.