I been on depo for three years and I stopped it a couple months ago my boobs are sore and my nipples are really sensitive me and my partner been having unprotected sex for 3weeks could I be pregnant !

It is certainly possible. Try a test. It can take some women many months after the last injection periods and/or fertility to return, but others will find it happens sooner than later.

Yes you could be pregnant. It is normal for breast/nipple soreness and sensitivity to develop soon after conception because the levels of hormones are increasing. It causes an increased flow of blood and changes to the breast tissue. As your body adjust the symptoms should improve.