Is my cat pregnant?

About four days ago my indoor cat accidently got outside for about 45 minutes. When I found her, the first question that automatically popped into my head is “Gosh I hope your not pregnant.” The next day she started acting weird, she was sleeping a WHOLE lot and eating a lot more and when she isnt sleeping she is cleaning herself. And to add to that, SHE GAINED WEIGHT. She is a very tiny cat, and I’ve read online that if your cat is pregnant that you shouldn’t be able to notice it until like four weeks into the pregnancy. But I was thinking that maybe since she’s such a tiny cat that im more able to notice it. And its weird cause when I pick her up by her shoulders, I can tell her tummy area has gotten bigger and she has always been a tiny cat. I’ve also read online that to tell if your cat is pregnant, you can look at her nipples, and if they are pink and swollen it means she is preganant. well I looked, and they ARENT pink, the are more peachyish. But I dont know that they arent pink cause maybe its to early in the pregnancy. But I dont know, im just worried so if you could please give me your advice I’d really appreiciate it! Thanks!