Are you being selfish absolutely not! I can see why you want this baby and i can guarentee you that you wont regret it no matter what happens with your relationship or family matters.
I am a 27 year old male and when i first heard that my ex wife was pregnant i was only thinking of my freedom going out the door. After the baby was born and to this date watch him grow up i undoubtedly say to everyone that it is the best thing in life that has happened to me and that having your child come up to you wanting you , hugging you and further on saying they love you is so preciouse that words can't describe.
So go for it girl what ever happens you will be right and the happyness that your child will bring you will be wonderfull.
Hope all goes well ScottyBigheart.