I have a white shaped large bump by my nipple incision: is this normal? (photo)

I agree looks like a stitch abscess, hopefully its just a single stitch and a simple removal will be all that is needed

The bump apoears to be from a deep suture that is working it's way to the surface. You should see a plastic surgeon to have it addressed.  It apoears you had a donut type lift and a deep purse string type stitch.  Unfortunately if that is the knot fron the stitch, removing it may result in your areole stretching out.  However, you may have no choice but to remove it before it becomes infected.

Dissolvable sutures require an inflammatory response by the body for their planned deterioration. Sometimes this can result in a collection of fluid around the dissolving suture referred to as a sterile stitch abscess. Your surgeon will drain this and it should heal quickly.