Do you think its wrong that I want to get pregnant at 18?

Serious stuff. Not sure if it is professionals job to pass judgment on personal decisions, but it would seem wise to seek information about the risks, responsibilities, and commitment that is required by talkign to a psychologist or other counselor. Discussing personal strengths, weaknesses, and life situation and the factors contributing to this question would be wise before making such an important decision.
That is your decisio. Decision, i know i was not even close to being mature enough to be a parnet or financially stable enough to be a parent at age 18.