I got her pregnant..now I'm not sure I want a child?

I'm 18 and she is 17. I really wanted to have a baby so I cut the condom tip before we had and it worked she's now pregnant. I was so stoked at first thinking we could finally be a family since we are in love and have been dating almost a year. She was very upset at first but now she's like all about being a mom. But now I think that i'm only 18 and I've basically closed alot of doors that would have been wide open. I mean like the world was mine, but now I'm trapped? How can i convince her to have an abortion? our thought processes have flipped.