It is natural for all of us to be a bit nervous before our wedding. But that does not give you any license to call off the wedding or run away from it. Planning a wedding can be really stressful at times. But that does not mean that you are stressed about the marriage. Learn to distinguish both kinds of stresses. You might have petty grievances with your partner about how disorganized he is or how casual his outlook towards life is. But that is not a reason for you to call off your wedding. It is important that both of you talk to each other and resolve any petty grievances you have.
The transition from in a wedding brings with it mixed feelings. It brings uncertainty as well as excitement. There is no reason for you to be scared of these feelings and run. This is a natural phase in all our lives. Enjoy it to the hilt. If you have any doubt in your mind regarding anything, it is better to clarify now instead of arriving at the altar with reservations. If you feel that you are not too sure to go ahead with the wedding, then postpone the wedding instead of cancelling it outright.