Yes it's totally normal. If it gets really severe where you can't function, there are antidepressants that are safe during pregnancy and will be so helpful especially afterward in preventing PPD. If it gets super bad, talk to your ob about it, otherwise try to rest... being tired makes it worse.
My first trimester I was very very depressed. Even went to see a psych. Of course they couldn't prescribe anything because I was pregnant and What they could I wasn't OK with taking. But my second trimester I started to feel better way better and I started to be less distressed and depressed. I'm in 3rd trimester now and it hasn't come back. I was thinking mine was just hormones and stress that me and my children's father was going through.early on. I hope it ggets better for you.
I think its different for everyone I definitely been depressed 80% of this pregnancy