My girls have a calcium deficiency I give 1ml per ...

Erm its kind of hard to tell how much of certain nutrient she needs unless you are very strict with your ec meter and mesuring your run off then it is possible to tell what she needs but your spot on defo does look like the start of a cal mag issue though where are these leaves on the plant if they are yellowing out towards the bottom of the plant and wortking its way up that can be a sign of a nitrogen defiency and though she doesnt need much N in flower she still does need it N like P and K are mobile nutrients within the plant meaning they are in constant use by the plant no matter the stage :) nice looking plant anyway pal im sure she will finish up just fine :) congrats 👊