I don't know if these are signs of heat as my kiddos are all fixed. My girl, Pfeiffer, humps her donut bed, and I'm fine with it. My 2 boys have a "lover dog" they have personal dates with
...and I don't stop it. It really doesn't bother me at all - as long as they don't hump humans, I'm fine with it as it seems to be a behavior they find comforting somehow.
As far as breeding, gosh, I so advise against this. You stated yourself how dangerous it is and that is SO true. Even the most experienced breeders experience tragedies. Are you prepared to lose your girl and/or the puppies? Bc it could happen. If it were me, I'd just allow this precious one to be a loved pet and I wouldn't put her through a whelping.