How can I relax when everything in my life is so unsettled?

I've been a single mom for the last eight years and nothing goes according to plan. I never know if I will get the kids where they need to be and I don't know if i will be able to get the rent paid or where we will eat or what? I used to have everything planned out and even though my marriage was rough (his drug addiction and alcolhol use) I still could fall back on his help and his family. Now it's live by the seat of your pants and this isn't how I enjoy life. Who could? Well I know that I wouldn't have made it this far without God and I know that for a fact. Does anyone have any advice on how I could just learn to relax with all this turmoil. Thanks for your advice. It is very much appreciated!!