The downward pull during an abdominoplasty is limited to the abdomen. The lower border breast has an attachment to the chest wall at the breast fold. This is quite secure and is not interrupted by the dissection is done during an abdominoplasty.You should not expect any change in appearance of your breasts.
Thank you for your question, best wishes. An in person consultation with a plastic surgeon should provide you with the best possible answers to your questions.