I also have a female that I intend to breed - she is almost 5 months old now - and I will be facing this issue soon.
I got a great nappy pattern from another member and I have made her a few nappies - they match her clothes, so it just looks like she is wearing pants.
I plan on keeping her in diapers when she is inside during the heat. We have a cream couch, so we will have to be careful.
She is already used to the nappy because I used it for potty training. It is a fabric nappy, so you just pop a sanitary pad in there and voila - doggie nappy.
Good luck
