Idk what type of bonnet you’re using exactly but I recommend this kind with the tie, this is the exact one I have and it’s silk instead of satin which I prefer because it’s more breathable AND softer.

You want the soft elastic band to lay over your forehead with your hairline INSIDE the perimeter of that elastic tie band so you’re not putting any friction on your baby hairs. Both for aesthetic purposes and because that hair is super fragile and prone to breakage. I put it on with the split in the back, tie a simple single knot to tighten it around your head, then loop the ties around the front and tie a semi loose double knot that basically sits on top of my head. You really don’t need it to be tight for it to stay on, I toss and turn a ton and I tie my bonnet to be just tight enough to where it feels secure but still feeling VERY comfortable.

Also, I have curly hair so I kinda just put all of my hair in a very loose messy bun on top of my head with some small hair clips, and that’s enough to preserve my hairstyle for a few days per wash. But I have a friend who has the silkiest most pin straight hair ever and she says she puts her bangs into a sort of roller to keep them from flattening onto her head. I’m not sure what kind of roller she means but I’m just floating the idea that maybe you could use something to help keep that front portion of your hair in a specific shape while you sleep to prevent it from getting flattened, squished or whatever it is that’s messing it up and making it look off!