need some advice for my indoor cat

Hi everyone, im new to the cat site and am posting my first thread. I have a female cat, i rescued from a shelter as a kitten named jazzy. She is a sweet, energetic kitty whose name fits her personality to a tee. Unfortunalty, she has developed some issues that i cant quite figure out and was wondering if you could give me some input on. I have an appointment to see her vet on saturday morning, but im needing some advice on how to keep her comfortable until then. She has been in heat for three weeks, i have to rescedule her spaying surgery until she is out of heat. She is peeing on clothes, and i have not seen her use the litter box to pee in the last few days as well. She does not have an appetite, which i was told was not uncommon with cats in heat as well as the peeing on clothes issue. Also she occasionally throws up her food, its not an everyday thing, just an episode here and there. One more change has been her demeanor. She is loving one minute, evasive the next, gets very excited and runs through the house like an energizer bunny and then will lay on my bed on a heating pad for the next three hours sleeping. she is very spookish or jumps at every little sound. This is not her normal behavior and i have tried new foods, toys, catnip, extra litter boxes, extra food and water bowls along with massages. Is there something else i can do for her? Also can i get some info on caring for her before and after her spaying procedure? How long does the surgery last? how long will she be out after? Thank you for any and all advice, it is very appreciated.

Her behavior sounds heat-related. A friend co-fostered a cat I found abandoned. We couldn't get an appointment to get her spayed for several weeks, and it seemed she cycled in and out of heat every five days. In the interim, she lost weight and developed some kind of skin allergy.
Nothing much you can do until she gets spayed. Some vets will spay when a female is in heat, depending on the circumstances; e.g., the cat is feral, too many male cats are around, or it becomes dangerous to the cat's health.) Meanwhile, I'd give her lots of love and attention when she wants it, but only when she initiates it.
Regarding post spay: The surgery under normal circumstances doesn't last long, maybe 20 to 30 minutes. She'll be 'out of it' for about 24 hours, she may throw up when she gets home due to the anesthesia, and her eyes will look really weird (change color, I think) (wish I'd known about this before.... ) I opted not to put a cone on her, but Ritz isn't a chewer. The vet said to limit her activity for about 48 hours. I didn't want her jumping onto the bed to sleep with me, so I opted to sleep on the floor the first night. She was back to her normal self within 24 to 48 hours and I didn't keep her from sleeping on my lap on the sofa Also, I opted not to give her post-surgery pain pills. I knew she had pain meds during the operation and I knew the pain would be temporary. And avoid Metacam, can have serious serious side effects.
I'll be counting the days until she can get spayed, I'm sure you will be too.

I came home last night and seen that she had threw up a hairball. Im going to look into hairball control treatments, and she seems to be coming out of heat today. She seems more like herself, no yelling or rolling on the floor, just sunbathing on the couch thank you for the advice. Im still taking her to the vet for a check up, and (fingers crossed) a date for her spaying.