You sure you did all of the ones on the overview page as well?

(3*30) + (2*100) + (3*150) + (100) + (40) + (3*30) + (100) + (300) + (100) + (5*20) = 1570 (Overview)

If you remove the 2 monthly medals you can't get yet and all 3 Zenith/ST missions. Total for overview is 720 points right now.

(5*15) + (40) + (40) + (40) + (3*20) + (4*15) + (4*15) + (5*15) + (3*20) + (5*15) + (3*10) + (5*10) + (4*15) + (10*10) + (5*15) = 900 (Dec)

(3*20) + (40) + (40) + (3*20) + (2*40) + (2*40) + (3*20) + (3*20) + (5*15) + (10*10) + (3*20) + (3*10) + (4*15) + (10*10) + (5*15) = 980 (Jan)

So end of the month the max you would have is 2600. If you minus the 2 collecting talents you don't have and sign in which you don't have yet, that means your current max total would be 2480‬. So it leads me to believe you have 1 20-point mission missing from the overview page. Which would likely be the Skill Trial one in the bottom right of the overview page. If you see otherwise, you'll have to contact CS to have them look into it.