I have a weird bump on my breast incision that feels uncomfortable, what could this be? (photos)

If this were earlier, I would suggest the bump is likely a suture trying to poke through the skin. That is unlikely this far out. I recommend placing warm compresses on the area to help it come more to the surface. I imagine it will resolve on its own.

Dear Yenny0803,
I understand your concern. However, without a proper assessment, it would be difficult to determine what went wrong. It is best that you visit your plastic surgeon for further assessment or ask for a second opinion. Only after a thorough examination, you can get proper recommendations and advice.
Daniel Barrett, MD
Certified, American Board of Plastic Surgery
Member, American Society of Plastic Surgery
Member, American Society of Aesthetic Plastic Surgery

You may have a stitch abscess, very uncommon at this time, or a clogged pore that is becoming infected. Please see a doctor and get treatment. You don't want infection to spread to your implants.

It’s strange having something after three years, but either way, you should follow up with your surgeon. The area should be opened. Might be a cyst which can form anywhere or anytime.

This is most likely to be the knot of the absorbable suture used to close the wound. It will either disappear in time, or it may discharge through the wound - it will usually settle down after that. It would be advisable to see the surgeon who did the operation for further advice.