situation

ive got about 13 liters brewing atm , ive noticed recently its just too sweet even after more than two weeks and 2nd brew , this could be i suspect because of 2 reasons , im increaseing the brew size way to fast and the scoby cant handle these leaps , and/or because ive been using yerba mate herbal tea the past few brews an its just not taking to it . should i boil a few organic black tea bags in a small amount of water and pour it in the boost things along?

I would say you need black tea, 2 parts black and 1 part green tea would be even better, IMHO. What you could do in future is make kombucha frim black/green tea and after ferment complete do a secondary ferment with the yerba matte and any fruit you desire. And on batch size, at least my experience, as long as you have proper proportion of starter tea intact the scoby size is not a huge deal, but larger ferments can take a longer time to ferment.