In Act IV, Scene 3 of Romeo and Juliet, what internal conflicts does Juliet express before swallowing the potion.

Juliet is conflicted by three different fears in her soliloquy in Act IV, Scene 3 of Romeo and Juliet. First off, she is afraid that the potion given to her by Friar Lawrence will not work and she will have to wake up the next morning to marry Count Paris. Her backup plan for this eventuality is the dagger which she has been carrying for much of this Act, and which she would presumably use to kill herself rather than marry Paris. She says,

What if this mixture do not work at all?
Shall I be married then tomorrow morning?
No, no, this shall forbid it. Lie thou there.

Her second fear is that Friar Lawrence may be attempting to kill her rather than be dishonored when it is revealed he has married Romeo and Juliet behind their parents' back and is then marrying her to the Count. She says,

What if it be a poison which the Friar
Subtly hath ministered to have me dead,
Lest in this marriage he should be dishonored
Because he married me before to Romeo?

She talks herself out of this and recognizes the Friar is a "holy man" and wouldn't deceive her. The third conflict is the one she fears most. She dreads waking up in the vault alone without Romeo by her side. She pictures the bloody corpse of Tybalt close by "fest'ring in his shroud." She imagines "loathsome smells" and "shrieks like mandrakes torn out of the earth."

Finally, after imagining Tybalt's ghost "seeking out Romeo," she musters the courage to take the potion which renders her lifeless for almost two days. Her fears, of course, are mostly unwarranted. The potion does work and the Friar is not attempting to kill her. Unfortunately, she does wake up alone in the tomb with Romeo dead by her side. The Friar arrives late but cannot convince her to leave as she chooses to kill herself.