Feeling down

Is depression during pregnancy a thing? I keep telling myself it’s just my hormones.. I know there is postpartum depression, but I feel as if it’s already started. I love my life and everyone in it. But so many times I feel like I’m sinking so far down that I can’t control it. I feel stuck and it’s like I have to fight to pull myself out of a dark hole. So I guess what I’m asking is, has this happened to anyone else? And did it get better or worse after the birth. I want to be the best mom I can possibly be. And I know my child feels everything that I do so I’m trying to keep it together but it just seems so hard