21 is not that young. I was 21 when I had DD. There may be other factors your family is thinking of, not just your age. Such as your housing situation, financial situation, employment situation, relationship situation. You can't let people pressure you into things and if you're ready and this is what you want, do what you feel is right. I just feel like people generally don't jump to abortion unless you're not in a good place.
I feel like there must be more to this story as well. Do you still live with your family? Are they worried that they'll be the ones to shoulder the burden? If that's part of the issue, you're going to have to think long and hard about whether you can afford daycare, housing costs, and the cost of raising a baby.
That said, you could also be in a good place with a good job and your parents could just not want a grandchild out of wedlock? We really need more information from you before we can offer advice. Adoption is an option, as PP mentioned, but I think it takes an emotionally strong ANGEL to choose adoption for her child... It's not something I'd ever be capable of.