Possibly serious question regarding my cat?

I have two siamese cats; one male and one female.
I’ve never had a pregnant cat before so I’m not entirely sure what’s going on, or if she’s even pregnant.

Fanta (female cat) makes this weird noise that sounds almost like a long continuous growl. And just now I saw this off-whiteish (beige) substance being released from her genitals. I’m assuming its her genitals.
I have no idea if she’s pregnant, in pain, or if she is indeed pregnant; her babies are in danger.
After she growls I hear this puff of air, or a sniff. I have no idea how to describe it. A sudden release of air from the nose?? Like a puff.

Excuse the fact that my question is poorly written; I’m extremely alarmed and would appreciate it if you guys answer ASAP.
I chose to ask you guys first before consulting with a vet just in case it’s not serious.