My senior seminar history paper was on Yalta. My conclusions were that Stalin kept the territory occupied by Russian troops. FDR had no way to change the reality on the ground. FDR wanted Russia’s help ending the war with Japan. FDR was sick and exhausted at Yalta. The idea that FDR could have gotten a better deal at Yalta is wishful thinking.
FDR looked like he had terminal cancer at Yalta.