Please note that we've updated the Mount & Blade II: Bannerlord save file system which requires you to take certain steps in order for your save files to be compatible with e1.7.1 and any later updates. You can find the instructions here.
Focus on just one faction at a time and leave the other to your allies. In order to force them to peace, you should beat their armies constantly. Form up an army around 1500-2000 and beat theirs at wherever they siege. It will take at least 4-5 big battles as AI somehow has the budget to hire like 10 mercanaries at once (Thank you, TaleWorlds). Don't take any fiefs from this faction because it'll only make the war longer. After considerably making them weaker, your allies will be likely to sue for peace and you'll have a short period of time to reclaim any place other faction might have taken from you. Do so, then take any fief that is close and also leave an enemy clan fiefless. Meanwhile pray that your allies won't dedice declaring war to someone else. Repeat it a thousand times and Calradia is yours.