It's wrong for other people to pressure you to go against your maternal instincts.
Most parents will be upset at first when they learn their daughter is pregnant under circumstances such as yours. Most of them get past it. You have to give them time.
I pray that God will comfort you and dry your tears. Follow your heart. Make sure you are taking your prenatal vitamins, and try to get enough rest. It's no good crying all the time. You can get past this. Take one day at a time. Tell the crisis pregnancy agency what you are going through. I'm sure they have some books that will comfort you. Also, read the Psalms. Other people have been through times of dark depression, and I think they will help.
We are praying for you, and we love all of you, including your new little one.
I'm sorry your mother is not 100% supportive right now, but I agree with the others who've posted that she will likely come around. I just feel so strongly that if YOU don't want to have an abortion, YOU shouldn't have one - regardless of what ANYONE else says. I have never known of anyone regretting NOT having had an abortion - but I know of way too many who have regretted having had an abortion...and then it's too late.
I'll say a prayer for you - that you feel strengthened and at peace with bringing your little one into the world. Some day, years from now, you'll look back at this time and be so incredibly grateful that you had the inner strength to know what was right for you and to stand firm in spite of the circumstances and attitudes of some of the people around you. In fact, you'll probably be hard-pressed to even remember all of the fears that are plaguing you right now - but you'll know the joy and love of your child.