Under two pounds grown is SO so tiny. If you are asking if any of us have heard of dogs THAT small being healthy and living long lives, I'm going to venture the guess that the answer is going to be no. Many of us here do have "tinies" (under the four lb standard minimum), but I don't even know if I've heard of anyone here with an adult dog less than two lbs.
It sounds like you had a rare experience to own and enjoy her even for as long as you did.
Many irreputable breeders, brokers, and scammers will claim dogs that tiny on the internet, but you need to be so so careful. I'm very very sorry that you found what you considered to be your "perfect" dog, and that she grew to be so dear to you, only to die so suddenly and unexpectedly. But if you want to avoid that happening again, I would steer away from looking for a dog that small. And actually avoid the term "teacup", which is usually a red flag.
I know you'll never be able to replace your precious baby, but I hope that someday you'll find the same kind of joy with another sweet and special pup. Good luck to you!