If it's her first litter, she may not have known what to do. That happens with many younger does. They aren't quite sure what to do and many lose their first litters from failing to make a nest or by not feeding them. Sometimes they make a nest and then fail to give birth in it. There's all sorts of thing that a doe need to learn when it comes to being a mom. Most breeders will give a doe three chances to get it right, then they eat her.
I would suggest keeping close records on when you breed her next and put a nest box in the cage when she's 28 days past the breeding date. Leave the box there until the 33rd day.They usually make the nest just an hour or so before giving birth.
I have had good luck in breeding a doe in the morning once and then again in the evening of that same day. I'll also breed her again the next day in case the first two times weren't good
enough. She's usually willing and the buck could always go again so I let him do his work. I consider this insurance.
I don't think that you're a bad breeder. Your rabbits and you are just learning and soon you'll be knee deep in fluffy little bunnies.
Good luck
Let me know if there's anything else I can help you with.