I am having doubts that my fiancee wants to get married
Why do you feel like she doesn't want to marry you?
She doesn't want to plan the wedding together with me.
Most people experience some doubts before a wedding, so you should talk to your fiancee about how you're feeling. Making assumptions about what she thinks is not helpful to anyone, and by sharing your feelings, you'll make both of you feel more comfortable.
I don't think it's such a big deal. I'm going to decide how the wedding should go anyway.
If you are sure that it isn't a problem, then I wish you well on your wedding!