Yes. Yes. Yes. I 100% think it is hormones causing your (and mine) peri menopausal misery.
I have always suffered with PMS. Taking the BCP never helped, and one brand I tried made me depressed and emotionally detatched all the time, for the year I was on it.
Like you, I also suffered with awful PND after my first child was born. I knew before I had even left hospital with my baby that something was VERY wrong. I felt like I was falling down a never ending, black hole. I was terrified and irrational, and felt filled with despair. With ADs and time, and a very supportive DH I finally recovered and was perfectly well for the next 10 years.
But after I turned 40 I noticed my PMS getting worse. For 2 weeks per month I felt very flat and depressed and angry. Then my periods started getting much lighter, and that was when things turned really scary.
I started suffering with insomnia. Then I started experiencing waves of dread. I felt panicky and on edge much of the time. I thought I was having a breakdown. There were days when I genuinely felt suicidal. Basically, it felt like I had PND all over again, just without a newborn this time.
I finally saw a specialist who told me that women who suffered with PMS were VERY likely to also get PND, and go on to suffer with anxiety/depression in the peri Menopause, too. It's purely that we can't tolerate progesterone. It's like mental poison for us.
I wish you lots of luck and hope in getting the help you need. But, rest assured, it is physiological fluctuations in your hormones that are causing most of your distress.