Postpartum depression

My baby will be 13 weeks in a few days and I feel like I’m just now getting postpartum depression. I’m high risk for it and have done pretty well until now. I’ve gone back to work for 3 weeks and my son is doing so much changing and maturing and I just feel like that could be contributing. Has anyone else ever experienced it this late? I don’t know if it could also be because I had such a difficult birth and recovery