Will my birds egg hatch?

Hi, your female may have not incubated them right away, which would delay the process. If they are fertile, and you know they are, no worries. I would just be patient and when they want to hatch, they will. If she was off the eggs for any amount of time after incubating, they may not have developed. Once they incubate, they have to stay on them. If they were in the nest for 3 weeks without incubation, they could still hatch, but once incubating, she has to stay on them.