Post partum depression

How can you tell if PPD is creeping up on you? I’m tired from my baby eating every 2 hours but I have barely any interest in doing anything but sleeping. I used to keep my house picked up everyday and I could have sex like 4 times a day with my husband before getting pregnant, now I also NEVER want or even THINK about sex. He’s always asking and I never want to anymore and I do it anyways to please him and try to get back to our normal but I literally couldn’t care less if we had sex or not ever. I’m only 21 and feel like my life is over and my sex life is gone. I don’t feel sad I just don’t want to get out of bed. When the hell does my libido get back up