How where nukes created in this timeline?

So,here’s the question,WW2 ended on 1944 right? That means the US never completely develops and drops the first nuclear bomb, but, the US in fact developed the bomb before the year 1945,so, the project is abandoned by the US army or it is still developed,also does Interalandia or the US create the first Nuke,are we in a dieselpunk universe? A NuclearPunk universe where the transistor is never invented? What are we in?