That normally happens during the later stages of pregnancy...

I would say it's puberty, but "weeks" is too short a time for that.

If you're not pregnant then it may be due to a hormone imbalance.

well maybe its not weeeks
but i just started noticing that
and I did just have my period
so i couldn't be pregnant

Its not whether you have your period, its whether you have had unprotected sex or not.. many girls and women dont know that you can still be pregnant and have a period... Some pregnant women have what's called "implantation bleeding" that can happen around the time their period is due, and they may mistake that bleeding for a period. This spotting may be caused by the fertilized egg burrowing into the blood-rich lining of the uterus, a process that starts just 6 days after fertilization, and it's generally a lot lighter than a typical period � just a day or two of very light spotting.

Please, its in your best interests if you have had sex to get a pregnancy test!

I'm currently pregnant and my nipples have gotten significantly darker, I know it's due to the hormonal imbalace that's occuring right now in my body. I do plan on breast feeding my baby, but my question is this, will my nipples get back to my normal pigmentation? After breast feeding?