I'm so sorry to read about your beloved Sasha. I believe that they know when it's their time to cross to Rainbow Bridge. My Cody boy, for the first time ever, willingly walked into the exam room on his last day. What a wonderful instinct. As horrible as it is, to watch a sick pet suffer even more is selfish. You did the right thing. Sasha did what she was meant to do on earth and is now happy and healthy and keeping an eye on you.
I hope you consider adopting. I think as much as you plan to get a certain breed or size, your heart will tell you which dog is right for you, the instant you see it. Out of all the lovely, wonderful dogs at the shelter, when Logan and my eyes met, it was electrifying!