27 and scared of motherhood

So I'm 27 years old, I am in a living relationship. I know I want kids before I'm 30, but the thought of motherhood still frightens me. I'm afraid I won't do it correctly or I'm going to have a baby and completely regret my decision... I know this sounds selfish but I'm sure I am not the only one having these thoughts. I don't want to wait too long either and not be able to have kids. I might regret not having them while I was able. Infidelity runs in my family around the age of 30-35. Anyone else having these problems? Any advice you can give me?