“You’re doing your best, and that’s all you can do. Hang in there.”
What I’ve learned about kids (after having five — no, really, it’s taken that long) is that some of what they are is how you raise them, and some of what they are is what is born in them. And some of it you think you can control, but that’s a dirty lie.
My first child (who is now, blessedly, 20) was a horrifically colicky infant. She cried for basically the first eight months of her life. It was not a good time. After we both survived those eight months, she turned into a sweet toddler. She wasn’t tantrum-y.
If I said, “Don’t touch that thing, it’s ouchy,” she didn’t touch the ouchy thing — because it was ouchy. We co-slept and then after a year she slept in her own bed. She went right to sleep without a fuss. She never hit. She never bit. She was completely delightful in every way.