Feeding twice a week might be too often. I only feed mine once a week and they seem to grow at a good consistent rate. Sounds like you definitely had a lock, I work a lot, so I often miss the locks, therefore I rely on the 3 days in 4 days out (people say 3 days out, but I don't have a ton of females, so I went with 4 days out, keeping everything on a weekly schedule to make my life simple). Like Don said, candling an egg means holding a flashlight against the egg so that you can see if there are veins in the egg. Youtube has some great videos of this that will make it obvious.