Not ready to be a mother

I don't know how I really feel about becoming a mother, and being pregnant. I feel like I'm sooo young at 20 and I haven't done enough in my life to really feel like I'm ready to have a child, I'm 35 weeks now and obviously it's no turning back now but I just want to know what I can do to put my mind in a better state of excitement  then ultimately feeling regretful.