What am I doing wrong. I’m noticing the leaves are turning yellow.

Hi mate! First of all, how do you know you are using THE RIGHT amount of nutrients? That "half of what bottle says" is just basic sentence for noobs so they won't over do it right away. Every cannabis strain basically has different needs for different nutes at different times and even the amount of light and growing media affects this. Don't want be rude just pointing out and to me the girls look underfed and having deficinecies. Not sure but I think there is nitrogen, potassium and maybe little bit calcium but nutrients interact with each other so it is not always so simple (Check mulders chart) I suggest that you start giving little bit more nutes overall. 👌