I'm new to this as well, but it sounds like you did start it off too weak. Rule of thumb: 8 tea bags per gallon, and 1 cup of sugar per gallon. I guess it's possible to add more sugar later in process but hard to stir it in without damaging the creature, or? Anyway - your scoby sinking doesn't...
I used blackberry tea for my kombucha and my scoby has turned black. Could this be normal and scoby is just taking on color of tea? Or sign of something wrong? Thanks.