check your in game map .. not all missions involve Amita or sabal
look for letters on your in game map ..map key on PC = M
B = Bhadra ( leads to a cutscene to tell you about your fathers home where you meet yogi and reg )
Y = yogi and reggie missions ..yes you must do some of these to keep the game progressing
L = logunis mission ..yes you must do some of these
N = mission for Norre
W = agent Willis missions .. you have to do all 3 of these to progres to the north region
H = Hurk missions
you'll also see a yellow symbol of two crossed swords , these are balance of power missions where you must choose to follow Amita or Sabal in the way they want you to proceed .. keep in mind your choices carry weight ..your told that early in the game ..siding with Amita all the time the game with a different outcome for the people of Kyrat then if you choose to follow sabal all the way .
the only way to play all the balance of power missions is play the game at least twice
once following sabal
once following Amita
if ya ever run out of stuff to do .. do side missions at your taken over outposts .. they give Karma and Exp points ..and some unlock new weapons and skills
also do the rabi ray rana mission ..to unlock propaganda missions ..and do not forget to go see Sharma Salsa at banapur outpost .. she will unlock the kyrati film racing missions