PROBLEM: I’m having trouble tying my paper together, especially with my introduction. It seems to me that my paper would not be solid when I am trying to prove two things. But I think it’s possible because one thing ties to the other. I’m trying to prove why Desdemona doesn’t have a powerful voice in the play, but instead she is mistaken for being rebellious with having a powerful voice.

Introduction: Anyone who read the tragic play of Othello can argue the fact that Desdemona can be the blame for initializing the tragic storyline which carries on after her first appearance in the play. However, the fact that she possesses a powerful voice is still an open discussion. From the content given in the story and what achieved writers have said in their analyses, it’s concluded that Desdemona’s power in her voice at the beginning of the story is overrated by many analyses on Othello. She never had a powerful voice from the start to the end of the story. A powerful voice can be a very subjective word with numerous definitions. Powerful in this essay is in the context of being persuasive, and having control of the situation. In Desdemona’s character, she does not display her powerful voice in the beginning till the end of the story. If she actually did have a powerful voice, the tragic storyline would have never occurred. The reason being, she had a lot of chances in finding out what was wrong with Othello to clear the confusion. Or even more convincing to Othello, she had chances to explain herself thoroughly, reasoning with Othello at the end of the story. Instead, her voice was limited and passive. Her powerful voice in the beginning of the story was only pushed upon Othello’s monumental authority that she relied upon for her powers in her voice. Therefore she can be seen as rebellious, but she does not have a powerful voice throughout the play.
Additional Details

2 hours ago
This is my outline to help you have a better idea of what my paper would be like. Outline
1. Introduction- Thesis: “Therefore she can be seen as rebellious, but she does not have a powerful voice throughout the play.”
2. Desdemona vs. her Father (Introduction to the prime example of her being rebellious. This example is when she is speaking for herself to her father. I will be using this to support why she does not have a powerful voice.)
3. Othello’s first scene as support on why she doesn’t have a powerful voice. (The first scene I would introduce is when Desdemona and Othello retelling their story to her father and the officials.)
4. Othello’s second scene as support on why she doesn’t have a powerful voice. (The second scene I would use as support is when Othello makes the decision on whether Desdemona would go with him to fight the Turks.)
5. Cassio (I will use Cassio as support that she does not have a powerful voice)
6. Conclusion
My two cents:

You are trying to say too much in your intro. I'd save the details for the later paragraphs.
I think Desdemona has a very power voice. Her voice was the only thing that would defuse the rage of her father when he complains that his daughter was a victim of witchcraft. If it were not for her eloquent and firm defense that she chooses to be with Othello, he would have been killed in the 1st ACT. Iago know her power when he suggested Cassio seek her for assistance in regaining his position. Notice that it would have been successful had Iago not poisoned Othello with thoughts of adultery accompanied with proof (although erroneous). It was her voice that ultimately persuaded Othello to kill himself at the end. Her background, her father and her husband lend her credibility that makes her voice powerful. But one must consider that she was not in a vacuum. No matter how powerful voice is context and circumstance always effect how people react to any given situation.