ok, so you are brainstorming your brain off right now - can I make a few suggestions?

Get yourself a notebook, the ones that have dividers in them are good. Write all your ideas down in the one place as soon as you get them. Keep it by your bed in case you get one of those middle of the night epiphanies.

Before you start to think about who you are going to tell about it, refine the 'business' itself FIRST. A vision/mission statement is a good start ie - to provide teen mothers with a safe xxx to xxxx when xxx etc etc.

Things will often flow from there, but you have lots to think about. You really don't want to weed out problems later if you want to be seen as professional, and it will save you stress down the track. Don't think globally right now - its too much.

Find out about current Teen Pregnancy support programs in your area. Are you going to be non-profit, donation based - what kind of $$$ do you want to make it viable?
If you want to apply for any grants etc, you must be VERY clear on the service you want provide.
What cases are beyond your expertise (drug issues/homelessness etc)? Are you willing to provide information/classes about birthing too?

Just some things to think about...!! Let us know how you go.