How can you tell if a guy "finished" after ?

I performed oral for the first time yesterday. My boyfriend got hard and he was breathing hard and twitching a lot so I think I did everything right. But at the end he went soft all of a sudden but I really couldn't tell if he d in my mouth or not; I did have a lot of saliva. My question is do you think he came? I didn't want to ask because that would just be extremely awkward. He wasn't standoffish or anything and we snuggled after so I think I did it right but I just don't know.