I remember about 30 years ago both times I was pregnant I would burst into tears at nothing during the first 6 months. One time I wound up sobbing uncontrollably over an episode of Lassie. It wasn't depression for me, I was happy overall- but I would just burst into tears so easily!
I feel for you. All good advice so far.
I do think it's good to keep all possibilities open in one's mind. I know that I have sometimes been certain about some cause/effect thing that later I found out was not what I thought it was- leading to various good solutions I hadn't anticipated at first.
Good luck to you in finding some relief.