I was going to say almost the exact same thing.
Your male probably has just not figured it out yet, 600g is no guarantee. Males can go young and light or they can take a season to figure it out and it's very frustrating lol. Once they figure it out they are reliable but I never chance a virgin male, always have a backup proven breeder male to get a few locks in if I don't witness the new male locking. If he is your only male, no need to panic, just be patient with him. Keep both male and female eating weekly and give them a couple days together every couple weeks or so. He will eventually figure it out.
As for females, exactly what Lord Sorril said. Weight is not a good indicator, age and body condition is what matters. Some are ready at 1200g and some not till 2000g. If your female is 3 or older she probably will be ready to go this year as long as she has been eating regularly and has a good build on her.