How do I know if I'm saved?

"If you declare with your mouth, "Jesus is Lord," and believe in your heart that God raised him from the dead, you will be saved. For it is with your heart that you believe and are justified, and it is with your mouth that your profess your faith and are saved. As Scripture says, 'Anyone who believes in him will never be put to shame.'... Everyone who calls on the name of the Lord will be saved." Romans 10:9-11, 13

What if I still have doubts?

"I do believe! Help me overcome my unbelief!" Mark 9:24