As far as birthing alone. Please do look into a doula (and just in case you've never heard that...a Doula is a birth professional who cames and supports you during your entire labor). Labor and birth can be stressful in parts and it could be a really nice thing to have another woman there who is with you and stays by your side to support you. A lot of OBGYN's can refer you to a Doula or even ask WIC. I have heard of some birth coaches being WIC counselors too. But I'm also sure that if you are in fact alone that the nurses in Labor and delivery will take extra special care of you
If you are in the U.S., 2 other programs you can look into are Early Head Start and Help Me Grow (they should be in the phone book). Both support pregnant mamas and children birth to three. They can help with a lot of your needs as a young new mama!
Good luck! And I completely agree with the previous posts in that I am AMAZED at your preparedness to be a mommy. You are a very wise young woman and I am so happy you have found these forums! Please keep coming back. I know that we would all love to support you and little Brandon in your next big journey.