Moses was stressed big time. God sent him back to Egypt to deliver his people from Egypt. Moses already told God he wasn't a good speaker. He was nervous but he was obedient. But his obedience wasn't getting the results he thought it would.
Moses might have thought if he tells Pharaoh the words of God and shows him the signs God gave him to show him (the stick that turns into a serpent, the hand that turns leprous) Pharaoh would say, "Yes, you are right. You can take the people."
But God was doing more than getting His people out of Egypt. He was going to show them and all the Egyptians how much better and more powerful He was compared to any world system, any god of theirs (especially Pharaoh -- they saw the pharaoh has the sun god). Plus, God was going to reveal Himself in a new way to His people. He says, "and I appeared to Abraham, Isaac, and Jacob, as God Almighty, but by My name, LORD, I did not make myself known to them." Exodus 6:3
God is merciful. There is always a lot more going on than just what we hope happens, what affects us personally. There is always so much more going on than we can understand. God will come through but in His time. Much has to happen. Sometimes whole worlds have to be shifted.