Make breasts more round without implant?

Depending on your body shape and size, you might or might not have enough fat to be used to shape your breasts. And that might be the best option you have if no implants are desired. But that being said, you should still see a board certified plastic surgeon who is experienced in different breast surgeries to understand exactly what you want and what procedures are available to achieve that. Since you mentioned tuberous breasts, there are actually different severities of tuberous breasts, you could just have a minor type.

Dear fautoe,
it is hard to tell for sure without an examination. If you are considering surgery, I would suggest you consult a board-certified plastic surgeon. Only after a thorough examination, you will get more information and recommendations.
Daniel Barrett, MDCertified, American Board of Plastic SurgeryMember, American Society of Plastic SurgeryMember, American Society of Aesthetic Plastic Surgery

The most predictable way to reshape the breasts in the way you describe is through a breast implant. That obviously though would mean more volume. To decrease the size of the areola you can consider an areola reduction. To learn more visit with a board certified plastic surgeon near you.