Haven't changed my last name

Mommy of 💙💙💜

So my husband and I have been married going on 3 years this November. I have still not changed my last name. And not because I don't want to but my oldest son has my last name. He was born in a previous relationship. So I always felt that i would be leaving him out because my husband and I have since had two children together. But my husband does want to adopt my son but he wants him to keep his orginal last name because he feels my son should make that choice when he gets older and can understand. Well recently I have been wanting to change my last name but just feel torn. I know it seems stupid and my son is so loved in our mixed family. I just go back and forth. Anyone else deal with this?