Hey Dawn, the thinking too much is a malady I have always been cursed with. I say to myself, STOP, and think of something else. Sometimes it works, sometimes not.
About the credit. Try getting a credit card associated with a store. They are easier than the big ones. And go from there. Do you have your own bank account? If not, open one. Good idea to check credit report.
Though I know its hard, try to go to bed the same time every night. You might toss and turn for hours but do it anyway. Keep the room dark and quiet.