Pregnancy hormones - myth?

Bridget
Hello! I'm super new to this - first time pregnancy and only 6 weeks - but my doctor just told me that pregnancy mood swings are a myth: As in, pregnant women don't get mood changes from pregnancy hormones. It's all a myth or paychosomatic/fake.
Is this true? Is this a scientifically-backed thing?
I had experienced long-term depression and anxiety before pregnancy (all managed now, woo!) and before I knew I was pregs (last week), I had a horrible "blue" day that was like the worst of my depression. Colours looked different, I felt wretched for no reason, couldn't think properly... Been super sensitive lately and couldn't figure out why.
Want to know if this is normal or if I should worry my depression's coming back. It's definitely not just in my head: felt like this before I knew I was pregnant.
My doctor was firm about there being no such thing as preg mood swings but so many people anecdotally seem to experience them.
(My doctor's a woman, if that makes a difference. :P)
What's your take? Have you experienced any mood changes or has your doctor told you something similar?
Thank you!