You're the only person that can decide what you want to do.
Just think that if you abort and when your due date comes around, how are you going to feel? What about every year when the day comes that you had the abortion, how are you going to feel then?
Do you think that at your age you could raise a child? (Im 16) Do you think you could give the baby everything he or she may need? Could you be a good mom? If your baby has a health issue could you deal with it? Are you ready to give up your teenage years and become a mother? Put yourself if your child's shoes, would you want you to be your mother?
If you put your child up with adoption, would you have the support that you need to help you get through it? Could you pick a good family out for it? Would you be abel to make that decision? Do you love your child enough to give them to someone who will love them? Would you want an open adoption so you could still have some contact with them? Or would you rather have no contact with them? If you have no contact with them, wouldn't it bother you that you have a child and have no idea where they are and will probably never see them?
You need to decided what the best decision is for you and your baby. Remember that it is not just you that you have to think about anymore. There is a beating heart inside of you that will need alot of love and attention. Could you give them everything they need? If you decide to keep the baby then they are your responsibility. Only keep your baby if you know that you can do it. Don't make another child suffer because a mother can't do it!
I personally do not believe in abortion, but you need to do what your heart tells you to. Does the father know that you are expecting? Maybe he can help you make the decision and maybe he will support you and your child.