It's good to be thinking about finding a queen, but it's somewhat rare for a queen to just disappear and the hive to not start some emergency cells. If you had 2 frames of brood 10 days ago and it's all emerged now, it tells us that the last eggs were laid by your queen between about 22 and 31 days ago. If any of those last eggs were raised into an emergency queen, she would have emerged between 6-15 days ago. Personally, I would wait one more week and inspect again looking for evidence of a new queen before purchasing a mated queen to introduce. If there is a young queen in the hive that you missed seeing, the bees will kill any queen that you try to introduce.
Joe