If you have a lump on your left breast would you contact your primary care or obgyn

It’s no longer pregnancy related so I’m unsure if I’ll get in as quickly as I did before. I know it could be a milk duct or some sort of cyst— but the more I read about it online. A hard firm, not always painful odd shaped bump should be checked out. I am pumping and attempting to breastfeed but I’m not successful. I am only producing colostrum 7 days postpartum. So I don’t think my milk is coming in, I’ve been supplementing with formula, since fed is best.