Mazal tov on your wedding!

During the clean days, wearing clean underwear on which any staining or bleeding could be discerned is a clear halachic requirement. Wearing white underwear (or colored underwear with a distinct white crotch) during the clean days is considered a binding custom. This custom should be followed unless there is a strong reason not to do so. If you would like to share your concerns with us, we may be able to suggest some practical ideas for you. 

When a woman is not in niddah, there is no halachic constraint on wearing underwear of any color, including white. However, wearing colored underwear when not in niddah is usually to a woman's benefit. If a woman winds up staining, there is a chance that a stain on white underwear (or colored underwear with a white crotch) will make her niddah unnecessarily, while she would not face the same issue if wearing coloreds. You can find more details on the laws of stains, and precautions to avoid becoming niddah from staining, here.

Please let us know if we can be of further assistance.