I'm sorry! I know exactly what you are going through!! Daisy came into heat 2 weeks ago and it has not been fun, but thankfully we only have about another week of it. I'm not sure the reason as to why they will not spay during heat, but I was told I had to wait until she got out. I have her scheduled now for November 20 which will be 5 weeks after she first went into heat. I used diapers even though she has now starting running & hiding when she sees me get them out. Daisy has actually slept a lot more too. I guess she doesn't feel the greatest.
Good Luck & 3 weeks will go by quickly!!