I am coming at this from a different perspective, based on different life experiences.
My advice – do not make a decision about adoption now.
Giving birth is an experience that cannot be described. It changes you as a person. You will not be the same person after you give birth than you are now. Allow yourself that experience. When you develop a close relationship with potential adoptive parents you start to feel like you “owe” them a baby, and you are somehow responsible for “fixing” their fertility issues. This is made deeper when you are a religious person having a baby out of wedlock. Sometimes that situation can be manipulated into thinking this is how you can “pay” for this sin and make it right. Then if you give birth, and find you cannot or do not wish to relinquish your baby, it can make things incredibly complicated.
Notice how very few people that advise women to relinquish their child for adoption, open or otherwise, are women who have done just that. You are asking strangers on the internet to decide what is best for you and your baby. And yes, the baby’s needs are extremely important, but your needs matter as well.
Here’s the deal. YOU are the mother of this baby right now. You may eventually chose not to parent that baby, but right now you are the decision maker. Take all the time you need. If your primary reason for considering adoption is that you fear you could not provide for the child, but really do want to parent, talk to a NEUTRAL therapist (NOT SOMEONE FROM AN ADOPTION AGENCY) and see if resources can be pulled together. Let someone help you examine your heart (yes that counts!) AND your mind to undercover your true desires, motives, and resources.
Talk to women who have relinquished newborns. As you can, with a variety of takes on it. Talk to those who were at peace with their decision, and those who regret it, and everyone in between. Talk to people with successful and not so successful open adoptions.
Talk to other teen moms in your area to get an idea of reality of being a teen parent. Talk to moms in their 20s and 30s who were teen parents to see how things turned out for them and their kids, and what factors contributed to, or detracted from, success.
You may indeed come to a decision that open adoption is the best option for you. But not because you need to “fix” another couples infertility, or because a stranger on the internet thought it would be better for the baby to have a stable two parent family, but because after examining your heart, mind and resources without pressures, YOU decided this is what is best for the baby and yourself.
As far as the POTENTIAL adoptive parents goes, it sounds like it is relatively early in the pregnancy. If you are having doubts, I would just bow out, and say that you are leaning towards adoption, but not ready to make a decision, and minimize contact and not set expectations you are not sure you can keep. It is OK to distance yourself for a while.
God bless you.