The light is not overkill lol and they are not too short... short plants get a chance to grow out rather than up... a bushy plant will produce more colas "more weed to smoke". and the most likely reason for the leaves turning yellow and getting blotchyafter your first feeding is that the nutes are too strong "THIS WILL NOT OCCURE BECAUSE THEY ARE TOO WEAK O.o"... try using plain water for one or two waterings or use less nutes...