While I'm not necessarily against it on moral grounds....I think it's one of those decisions that you will regret later in life. Parenthood is a truly wonderful thing. Children can be pains in the ***** at times (and lots of them), that's for sure. But the love for your child is a love like you've ever experienced before. And while it seems like a good idea for the here and now....in 5 years the regrets might be worse than any potential financial situation you're in now.....
I became a father at the age of 16 (conceived when I was only 15). And I wouldn't change it for the world.
And, not advocating "welfare parents", but the government does have a ton of programs to aid parents in not-so-well off financial situations. Don't be ashamed to use them. Hell, you helped pay for them.
Though I would wait to freak out until a doctor confirms it. She's still pretty early...I believe most tests need you to be closer to/over 4 weeks to really be accurate. Or...maybe her conception date isn't what you predicted //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif