Breast lump?

So at the end of last year I had my left breast checked because it was leaking a bit of fluid. They took pictures and said they found a mass and sent me to a specialist. I went into the specialist expecting to talk about a mass and all she discussed was lymph nodes and sent me on my way saying nothing was wrong and there was no biopsy done on the mass. Fast forward to now, I'm 19 weeks with my first child and I noticed that my left breast is enlarged on the left side where they found the mass and feels firm and looks nothing like my right breast looks like, which obviously looks normal compared to the left which is more rounded with one part that seems to be stuck out a bit more like there's something there. I'm freaking out because I'm worried that they may have messed up and read the wrong stuff and sent me on my way with a deeper problem than they thought I had. I'm going to get to the doctor tomorrow if possible, but was wondering if any of you could tell me what it could be before I head in so I could be more prepared?