Sending you love! It is so tough when they’re young, and yes, it does get better. For me, it got better after my DD turned 1. She started sleeping through more often than not, and her reflux had cleared up. Her reflux was caused by allergies, which may be something to consider (but also, lots of babies have it without allergies).
All I can say is you need more help now - even if that’s just giving baby to your parents for an hour so you can nap, or asking your DH to take her more than once on a weekend. If family isn’t an option, and you can afford it, could you hire help? Either a person or some kind of daycare/creche. I joined David Lloyd just for the crèche, and they take from 12 weeks. It just meant I could guarantee an hour off to relax, either to exercise or just sit in the cafe away from my baby!
Finally, if it does get too much, don’t be afraid to take a minute for yourself. Sometimes, I would put baby in the cot, just so she was safe while I had a minute or two to breathe. Yes, she screamed, but I needed it!
And, randomly, I recommend noise cancelling headphones. They made witching hour tolerable (if still not enjoyable). Of course not to be used if you aren’t with them, but when I was spending hours cuddling a baby who wouldn’t stop screaming (and I knew she was safe since I was literally there), I used them. I didn’t even listen to music, it just dampened the noise.