TOTALLY normal.
However...
Pregnancy hormones do weird things. Most people get happy glowy from pregnancy hormones. Bipolar people usually 'even out' on them. And for MANY women the sudden lack of them cause PPD. SOME women, however, get antepardum depression.
Antepardum Depression is as misery making as PPD, it's just far less common. It runs in my family, so I didn't even realize it wasn't normal. My OB / midwife team were HORRIFIED I didn't say anything until after he was born (spontaneous / excited utterance I was so surprised/thrilled about not wanting to die the next day during my usual 'suicide hours'. Antepardum depression expresses in several ways ... A common one is having 'suicide hours', where for a couple hours every single day... You just want to die. It's a running joke in my family, because it's really, really awful. For all of my 2nd & 3rd trimester somewhere between 5pm & 7pm I'd rock and cry and scream and just literally hold onto my chair (or go completely still) to keep from killing myself.
Then almost 1 hour later, I'd be just fine. The rest of the day? Just fine. NOT happy/glowy but not wanting to die, either!!!
I was first in my gen to get pregnant, so via ME we found out that APD doesn't have to be suffered through and laughed art, anymore. There are antidepressants that are safe to take while pregnant. Doh!
The upside of APD is that typically starting on day 1 after birth, you feel over the moon happy. That eventually wears off, but it's helpful for the first sleep deprived year.
SO... Point being... If it starts getting WORSE; sadness, anxiety attacks, suicidal thoughts, homicidal thoughts... TALK with someone about it (OB), because there is a fix. Hormones do reeeeally wacky things!!!
But also remember... With #1... You still had good sleep and a life of your own. Having a toddler you're responsible for, sleep dep, and 'BTDT' / pregnancy isn't a 'surprise/fear/excitement/fear' is a game changer. You've already ridden this ride and gotten the teeshirt, so now it's not excited fear, but TIRED fear because you know what's coming and ... Yikes! But what about?!?
FYI, #3 is a similar game change, because you've already got how to manage another kid while pregnant DOWN. (Sayibg in my family : 2 is 3x the work of 1, 3 is HALF the work of 2, and 4 on out just gets easier s d easier).