3.5 year old whines 24/7

I’m at my wits end. I just don’t know what to do. She whines all the time. It’s hard to take her anywhere and I just don’t know how to help her. Everything upsets her or overwhelms her. She has been tested for autism and sensory processing disorder and she doesn’t have either of those, but something just isn’t right. Kids her age are not acting how she acts, and she has great verbal communication so she can speak instead of whine but she just whines all the time. I have tried all the parenting styles and nothing changes this behavior. Does anyone else have a child like this? Is there anything that helps?