We use lots of old sheets, chuck on on the sofa and pop one on the floor although at this stage many bitches will keep themselves quite clean. Tbh you may only find a couple of tiny spots around but putting an old towel or something easier to whip out and wash every day than her whole bed on top of her bed I find helps. Wherever they are the most and where the sleep are the main areas of splotches.
I would take care walking her if you live somewhere you walk in a communal area. First stage she will be decidedly unhappy about attention and may get snappy, clingy and miserable, second she will flirt up a storm and you will be invisible she will then usually snap and snarl at trying to be mounted, lastly she will be out for anything she can get and will stand - the problem is you cease to exist and even if you keep her on a lead it's distressing for the dogs and for your bitch up until she's hot to trot, and then it's time for you to practice parenting teens because once she's good - wherever there's a willy there's a way. Which is why in our rescue we had Rottie x Chihuahuas. I would really stick to quiet times and road walks tbh especially if she's feeling a bit rough. I don't walk mine at all but appreciate I'm able to wear them out in the space we have.
She may just want to snuggle up to you, my bitches have been split between no different when in season or clingy and miserable. She may want a bit more reassurance or stick to you like glue, it all passes. Her appetite changes are quite usual and I would be careful about adding tempting things as tummies can be more sensitive during a season or she may eat it all and then be sick.
There are drugs to stop pregnancy if she gets mounted but due to how they work it's better to prevent rather than cure.
The only other thing is to stay vigilant about signs of pseudopregnancy - nesting, appetite changes, mammary filling- the vet will check this before they admit her to be spayed and may send you home or prescribe galastop, depending on a few factors. So if you see anything that makes you suspect it have a chat to them and they can work with you to spay her at an appropriate time.
And you'll never have to put up with it again .