my nipples are way darker

So a few days ago (5/6 DPO) I took a photo of my nipples (in a dark room with front flash) and today at 8/9 DPO I took another photo (dark room front flash) and my nipples are like 2 maybe 3 shades darker.
I also have my nipples pierced (for a year and a half now) and one side is super sore and my nipple seems a little swollen, has never happened to me before and my piercings are 100% healed and have been for a while..
Good signs?