I started taking birth control a week ago and it dried up all my milk. Do I have to wait 3 months before getting a reduction?

Hello and thank you for your question.
It is preferable to wait 6 months after stopping breast feeding to have any breast surgery. Schedule a consultation with a board certified plastic surgeon to discuss your options. Best wishes!

Thank you for your question.  Typically after a pregnancy it is suggested to wait approximately 3-6 months after giving birth or stopping breast feeding.  It takes a bit for the breast to come back down and settle after pregnancies.  I would suggest seeing a Board Certified Plastic Surgeon in person to evaluate and discuss your options and questions.  Best of luck to you. 

Following breastfeeding, it takes at least 6 months for the breasts to adjust in size and shape. In addition, there is hypervascularity of the early post-pregnant breast which increases operative risk. 
I recommend waiting until the process completely subsides before contemplating surgery. 
Visit a board certified plastic surgeon for in-person evaluation and discussion.
Best wishes...