Baby name regret

My son is 2.5 weeks old and I think I want to change his name. I have until he is 3 months to make changes to his birth certificate but I don’t want to wait too long. Our 2 year old doesn’t really know his name yet as we just call him baby so I don’t wanna wait til he does and confuse him or anything. Idk basically I just feel guilty for not loving his name anymore. I just look at him and he doesn’t fit the name :( I feel like this has been such a struggle and I finally found one I THOUGHT I loved but it just doesn’t feel rite. Has anyone ever done this before? Why do I feel badly about it?