As everyone is saying...it is not your fault! Cats are fast and we can only do the best we can. You are a fantastic catperson. If I were a cat I would want to belong to your colony.

I would not remove the food from the porch (hungry strays milling about seem even more scary)...but I would spend some time there. Hopefully she will come home soon... I would also contact the vets and animal control to let them know your pet is missing in case someone finds her.

Blessings. You are the best.