Help!! Health insurance expired and I didn’t get COBRA info. What do I do?

I have a BCBS plan through my employer. I work as a teacher so when school ended in May, I told them I wouldn’t be returning the following school year (I was pregnant and having my baby in August). I called my insurance in June or July asking when I would get cobra and they said my employer hadn’t put an end date on my employment and that I still had coverage.

Today I found out my insurance has been essentially cancelled. I can’t log in to my BCBS planner app. I gave birth mid August and all my claims were denied. Apparently my coverage expired Aug 1. However there were claims from Aug 15 that were processed and approved, just only the claims from my birth were denied. I never got anything from COBRA even though I reminded my HR before I left and gave them my updated address and everything. It’s now the end of the month and I am stressing. I can’t call them until Monday. Where the f is my cobra paperwork like I was supposed to get? Am I missing something ?? I’m freaking out.

I am not from the USA and I hardly know anything about insurance here. I really thought I had this under control and I was totally willing to get COBRA and pay for it. I’m so frustrated right now. Obviously since I gave birth the bills are outrageous and I can’t afford it. I need to fix this ASAP. Today is a day where I really miss the healthcare in my home country.