Since you seem, from your previous posts, to only have a problem with pregnancy because it is a third child of the same gender...I am having a hard time being compassionate. However, having chosen an abortion while in my early twenties I can assure you that I always wish I had chosen to carry the baby and keep it or give it up for adoption. I still, ten years later, remember the exact date and many years I still cry about it.
It is easy to say now that you think an abortion would have been easier. There is no way to know how it will affect you unless you actually go with it. At the time, I was absolutely convinced that it was the right way to go--three miscarriages after that I was convinced that I was being punished.
I think you are still struggling with the decision at all. Having two children already, you know all the joy and struggle that comes with kids.
That all being said, I think you should get some adoption counseling. If you want to get to know the people who will raise your child, the time to start looking is now. If you want to make a clean break, then simply contact DFPS and ask how you can turn the child over to them to make arrangments. If you just want to do it nearly all, if not every, hospital that has a maternity ward participates in the "Baby Moses Law" and you can leave your baby there without fear of being charged with abandonment.
I know you are struggling. Please find some help for your health and the health of your family. Take the time you need to grieve and close this chapter on your life.