The cannibalism thing is quite common. I have seen frogs close in size try to eat one another. It's just how they are. It is tough to get another frog once you fall in love with your first one. Keeping a look out for adults on forums, classified adds is the way to go, though you can wait for some time that way. Setting up a grow out tank is a good option too, but a real hassle to run two tanks sometimes. I have gone both routes to build up my group over the years.