Congrats on the first egg!
I'm not an expert on what kind of hen lays what color egg, but I've heard that the comb and wattle redness is an indicator too, so If I had to take a guess, I'd say the New Hampshire too. I figured out which hen lays which egg just by running out there a lot (I was veryyy excited when I first got my hens and they were about to lay) so I'd catch them in the act, then wait for them to finish, and then I knew which one laid which egg. Quickly enough, I knew all the hens egg colors, sizes, shapes, textures. So, maybe if you can, head out every once in a while and see if you can catch anyone in the act. This is of course the long method (there has to be an easier one, right? cameras maybe?) and hopefully someone else knows a more efficient way to know.