Baby blues vs PPD?

I’m about 3 weeks pp and I have days here and there where I cry.. and not about anything in particular usually..I’m EBF and it’s been going great for us but I think that overwhelms me sometimes? Today at my moms house the baby started crying because he was hungry and people kept wanting to hold him and that for some reason made me cry. We ended up leaving early because I didn’t want to talk to anyone after that. My fiancé told me to call my dr because he’s “tired of dealing with it.” Which made me feel even worse. I’m not sure it’s serious enough to tell my dr about?