Is/Was she in heat?

Never having had a cat that wasn't "fixed", and having had almost all males, I'm a bit perplexed. Fwan's Kaylee and Teufel are staying with us right now, and I think Kaylee was in heat, but I'm not sure. From Thursday to Saturday, she was noisier (lots of meowing) and more affectionate than usual, and kept throwing herself on the floor at our feet and rolling around. I didn't notice her raising her rear end, though. Teufel (fixed) was sniffing her rear end a lot, and Jamie (also fixed) was doing the "flehmen" stuff whenever he came across her scent in the house. A neighbor's non-intact male is spraying outside our house a little more often than usual. He and Jamie have a long-standing "p*****g contest", but Gismo normally doesn't spray the house itself.
She's 7 months old, and hasn't been spayed yet. I called my vets' office, and they can't fit her in this week, and next week she'll be back home.
Today she's still affectionate, but much quieter, and isn't rolling around any more. She seemed to be cold (shivering) this afternoon, so I put her under a heat lamp and cuddled her, and right now she's bouncing around again.
How long does "heat" last, and does it sound as if she was in it, or was she just being "needy" because she misses her meowmy? She's eating, and playing, and now seems to be seeking the "normal" amount of scritches.

Sounds like she is to me, and yes, they can get the shivers when they are in heat as well. It can last 1-3 days sometimes longer depending on the stimuli available- if an intact male is spraying that can prolong it. If she is continuously crying for 3 minutes or longer that is her mating cry and you need to safeguard her so she doesn't get outside- that male spray is a powerful magnet for her. To bad you can't get her in to get her spayed tomorrow-

My vets only do "routine surgery" on Mondays, Wednesdays and Fridays, and this week they're all booked up. Right now, she seems fine, but I'm really hoping that she doesn't start up again. She is an adorable little cat, and into everything. Both of them have had a few short encounters with Jamie (they're too quick for my old bones), and Jamie seems a bit more willing to accept her than him. He's growling and hissing, but not attacking, as he usually does when his space is invaded,

I agree with Hissy. Be extra on guard that she doesn't escape outside...

The cats have to get through three doors to escape out back, and two to get out front. Our big problem is the windows. We had the ones downstairs replaced last week, and the "Pet Screen" barriers won't be installed until Tuesday. The cat net we had disappeared with the old windows, as the hooks holding the net were held by screws bored into the wood. The new windows have synthetic frames, which you can't bore. I just hope that the Pet Screen is enough to hold all 6 kilos of Jamie back. He's very much a "bull in the china shop".