Everybody has self-doubt. Even the most confident person you know is wondering on some level if they are on the right path. Self-doubt is normal and should be considered a safety mechanism that constantly has you reevaluating your choices.
Don't let self-doubt hinder you from making the choices you need to live a bigger, fuller life. Question your thoughts. But then make fast, smart choices with the best information you have at the time. The people in life that are held back are those that get paralyzed by their self-doubt. Exercise emotional intelligence. Be aware of your self-doubt. But then push through it.
There are amazing things waiting on the other side for people that embrace fear and use it to their advantage.