Is my cat going into labour?

So my cat is pregnant and probably due any day now. About 9 hours ago she started crying for me and wanted me to sit by her nest with her. But when I sit with her she starts dozing off. She also purrs loudly and looks like she's breathing heavy (but it's not fast breathing, like heavy and slow). When I don't sit by her nest she meows at me or my sister until one of us sits with her. The cries sound almost as if she's in heat. She doesn't seem to be in pain. She's a pretty small cat. I've had pregnant cats before but none of them acted quite like this.

Is she starting to go into labour? Or does she just want someone to be around her because she might have them soon?