Hi Lindsey -
I don't mean to offend you in any way, but please really think hard about your decision to try to adopt your nephew. I know he is still very little but, as he grows, there will be all kinds of issues that he will have to face, if he is still in a familial relationship of any kind with his birth parents. You mentioned that his birth-mother is also trying to regain custody of him, so she, obviously, will not be supportive of your adopting him. Therefore, you will likely never be able to resolve any issues with her, much less minor things like who he should call "Mama". This will just lead to conflict and stress in the poor little boys life, not to mention your life..... Forever.
In addition, there is obviously a reason that CPS took him away from your brother and the birth-mother. He should never have to be subjected to even the chance that they could ever have any significant contact with him, much less becoming his "Aunt and Uncle"....
Think about the future.... What are you going to do when he's 13 and runs away to one of them? What happens when they make huge mistakes in their lives and he has to see it or, at least, know what is happening. This type of thing really damages a child!
There is a very good reason why most adoptions of infants are closed adoptions. It is so that these little babies can grow up and have as stable and as drama-free of a life as possible, without the interference or knowledge of the issues of their birth parents. You are very generous of heart to want to protect your nephew and give him a better life, by adopting him. But, don't forget that the current foster parents already love him and want him, too. Many foster parents dream endlessly of the day when they will be able to adopt one of the children they care for and make them a permanent member of their family. And, they are already tried, trained and tested "good" parents, so you know he would be with a wonderful family. Also, many foster parents are unable to have children of their own, and they would cherish the baby even more. Also, remember that adopted children are even more special, because they are CHOSEN.
You sound like a wonderful person, who wants to do the best thing to help your nephew. Please think long and hard and seriously consider giving him the gift of two loving parents and the freedom from all the drama that his birth-parents would forever add to his life.
God Bless!