Im so sorry for your loss. I know that grief over pet loss can be powerful. I hope you find the strength to endure these emotions.
If it's really meant to be, you can't miss the opportunity. Try not to dwell on the dogs you can't yet rescue and just let yourself grieve and prepare for the dog you will be able to rescue.
I remember when we decided to adopt a dog I started scouring www.petfinder.com
and visiting the local shelters. I even volunteered at a shelter and started getting attached to a deaf overweight Dalmatian. But we weren't ready for a dog. We still lived in a small apartment where dogs that size weren't allowed. I was so sad when I went into volunteer one day and Shadow was gone, she'd been adopted. But I feel like it was meant to be. The dog we later adopted is a better fit for our home and family. And I'm pretty sure Shadow got a good home.
Is this related to feelings about adopting a child? I'm just curious as to why it's in the adoption and foster parenting section rather than the pet section.