By comparing your screenshots, I think you probably wasted too many MP on getting the Berber lands with its +100% core creation cost?
I had an MP problem before I moved in on the Berbers, most of Italy was taken in the last 50 years, not that the Berbers helped any. Maybe its just because I took things so slowly with diplo-vassals and all before I went crazy towards the end. I have been overextended for the past 65 years. Another thing I neglected to mention, was my ideas were only 5/8 if I remember correctly.