Yep. I got it around 7-8 months post partum.
Do whatever you can to get a good night's sleep (i.e., ask DH to take one for the team and let you sleep with ear plugs one night).
And call your OB and tell them you're struggling.
Take this assessment too:
https://psychology-tools.com/epds/
That's what confirmed it for me, that I wasn't just tired, that it was more. A low dose of zoloft, therapy, and some major self-care helped turn things around over the course of a couple months.