I'm consumed by doubt right now
What are you worried about that makes you consumed by doubt?
I'm worried my lover is not what I thought she was.
You should not let your doubts consume your life and ruin opportunities for you. If you feel doubt you should talk to your partner about them.
At least I know that she's not cheating on me.
That's good, but you should still talk about your doubts. This will help strength and deepen your bond.