Peggy, I wonder where your fear of having a panic attack comes from? It's never actually happened, but the fear of one may be strong enough to bring one on. So maybe you need to face that fear and kick it in the butt!
Can you write a list of all the things you do with your children? Really notice the things you do successfully every day - you feed then, clothe them, comfort them - and I bet loads more. Then perhaps add some photos to your list of you doing stuff with them, of you laughing together, or having a cuddle - anything that reminds you of what you DO do for and with them.
I have a strategy that might help. When you are having a panicky moment, firstly acknowledge it and name it. Notice where youvfeel it in your body. Then breathe in deeply, filling your tummy up like a balloon, hold your breath a few moments and then release slowly through your mouth. Do this 3 - 5 times. Then look at your list of things you do successfully & focus on it for 30 seconds at least. Then notice any differences in how you feel. Choose one of the things you already know you do successfully and go do it now!
When you breathe like that it will slow down your heart beat. It will also be hard to think of anything other than breathing - which will interrupt your panicky thoughts.
I would also start to notice when you manage an hour/mornjng/Afternoon without feeling panicked, and pat yourself on the back. You need to make your mind focus on what you can do, rather than what you fear you can't (which as you say has never actually happened).