No period for 10 months after giving birth

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Hey everyone, I gave birth to my son on may 20,2019. And have not had a period at all since before I got pregnant in like august of 2018. I get pain! In my uterus a lot but never get a period I have taken way too many pregnancy tests because I’m paranoid but they’re all negative but I just have pain in my uterus and mood swings so much chaos this happened to anyone else ?