So, if I read your post right you had to lower your saddle 5 to 7 cm to meet the 'formula'? Assuming your riding before the lowering of the saddle felt comfortable, then the obvious conclusion is the formula does not fit your body and that bicycle geometry. 5 to 7 cm is a huge amount to lower a saddle if it was already comfortable. Raise it till you don't hurt. I'd suggest going up 2 cm to start.