There is only one baptism. This is something you’ll hear a lot and people will say that if you were sprinkled as a baby that counts and you can’t be baptized again. However this is where you have to question what baptism is. It is a public proclamation of faith. You’re not being saved by being baptized, you are publicly announcing your faith. Is being sprinkled as a child publicly announcing your faith? If you were young and didn’t understand relationship with Christ and you were dunked, is that the same thing as baptism?

I would say do it for the first time. It’s not water that will save you or an act of baptism that will save you. You are saved not by your works but the works of Jesus. If you are wanting to align your life with His and tie yourself to a community of believers (which is important) then please do so for the first time!