Of course she's your baby, of course you could raise her. 18 is adult age, and lots of women 200 years ago had children far before then, and managed to do a damn good job at raising their kids. And lots of women who have children in their teens these days do a damn good job at raising them too (I for one can't think of myself as a bad mother, and I had my son at 17).
You probably will not be able to cope with working and going to college at the same time, you will have to pick one. But wouldn't that be a good enough sacrifice for your daughter to be able to be raised and near her real birth mother everyday?
I know college and children are possible, because I cope. And what's more, i enjoy it, and I could never imagine not having my son near me everyday, and I'm sure he wouldn't imagine it either. Other women do it too, and they're not superwomen either.
Whatever you put your mind to, you can do.

I wish you all the best. Follow your heart.