5'3", 128 pounds with a 32dd bra. How small will I be if 325 grams are taken from each breast? (Photo)

150-200gm is roughly one cup size. 
For your frame, C cup might fit the general shape of the chest. Please consult your surgeon 

Thank you for the question and congratulations on your decision to proceed with breast reduction surgery; this operation tends to be one of the most patient pleasing operations we perform.There is no direct correlation between the amount of tissue removed and the ultimate cup size that a patient will wear after breast reduction surgery.Before undergoing the breast reduction procedure it will be very important to communicate your size goals with your surgeon (who you should choose very carefully). Most patients wish to achieve enough of a reduction to help with their symptoms while remaining proportionate with the remainder of their torso. With the goal of improving communication with my patients I find the use of photographs of “goal” pictures (and breasts that are too big or too small) very helpful. I have found that the use of words such as “dramatically smaller” or “C cup” or "proportionate" means different things to different people and therefore prove unhelpful. Also, as you know, cup size varies depending on who makes the bra; therefore, discussing desired cup size may also be inaccurate. Best wishes with your breast reduction procedure; hopefully you will be very pleased with the outcome of the procedure performed.