I feel for you. My first child was a very colicky baby for a full year. He was the worst spitter-upper, to the point that the doctor thought he had pyloric stenosis, where the pyloris muscle is in spasm and the breast milk or formula cannot go and stay down. We thought he would need surgery at 5 weeks, but it turned out to be “only” really bad colic, B”H. My husband and I took turns sleeping for nearly a year. The baby slept 15 minutes of every hour. His longest stretch was shy of 2 hours. Not easy. But I am still here nearly 36 years later, B”H, so gam zeh ya’avor for you as well.
I would strongly recommend that if the baby is not vomiting or ill in any way, that you get a set of earplugs and let her cry. I would never do that with a newborn; they need to learn they are safe and secure in their parents’ response to their needs. But by 8 months, your daughter is training YOU, not vice versa. Put a fan on in her room, for white noise (she might be a light sleeper also), and then lovingly say good night (very good to have a specific routine done every single bedtime, including saying shema to her and singing Hamalach). The continuity will help her to self-soothe.
I am blessed to be able to babysit for my ainekel every weekday morning, and he knows that naptime (he is just shy of 2) means Bubby will hold him on her lap and sing “aileluli” a Yiddish lullaby my mom O”H sang to me. He knows without my saying a word that he will put his head down on my shoulderas I sing to him and rock him gently, and then he has lately begun to sing along – slightly off-key (which unfortunately cracks me up, and thus spoils the ambience I am trying to create).
However, where this used to put him right to sleep in thirty seconds or less, now he only needs to be put into the Pack and Play after singing with me for a few seconds, and he puts his head down and goes to sleep on his own. Kids learn quickly, and they love and need routine.
Hatzlacha rabbah. I DO know how frustrating this is. I never had such a problem with any of my other children. And I wish you to see the same ease that I had with my other kids. There IS a light at the end of the tunnel.