Tadpole help

I recently got into dart frogs a few months ago. I have 2 azeures and 1 auratus froglet, and have a cobalt tadpole. I have had it for about 3 months now, and its front legs have not separated from the body yet. I temperature in the room is 74 degrees. Is this slow growth for a tadpole? Should I raise the temperature in the room? The froglets are doing great and are growing very well but are quite fat. Is this normal too or are they over eating?