Abortion is your choice, but there are soooooooooo many families out there who would love to have a baby, and just physically can't. I have lost 3 of my own due to various medical reasons, but we still want to keep trying. A baby is a blessing, and if you aren't ready for this baby, you should look in to adoption agencies. You can choose a family who can provide the kind of love and financial support for your baby that you would've wanted for him or her. There are also open adoptions so that if you want your baby to be able to eventually contact you when they're older, your information is available to them.
As far as your mom goes, she will probably be upset. You are young, and obviously not totally ready for a baby if you are having doubts. However, this baby is also her grandchild. She will probably be upset at first, but as time progresses and you start to grow and feel your baby kick, she will undoubtedly become excited. Once you tell her, then go from there. What's the worst she can do? Yell at you? Talk to her. Tell her your plans, share your fears...Moms can be incredibly comforting in times like these! Then once that's past, you can move on and start planning your life for you and your little baby.
also, no matter what you decide to do, please, in the future, use protection. At least a condom! Not even just a condom, use the pill as well, if you don't want any more babies just yet.
goodluck and please, keep me updated. I will be here for you if you ever need to talk, just message me!