Doe mating, but no litter (Update!)

I will try to get pictures up so you can see what I mean.

I'm going through a similar situation. I wish I had answers too. My 2 yr old proven doe had a litter 5 wks before we bought her, and was bred right when we got her, but since then we've tried twice with no success. She lifts for him, the buck has had 3 successful litters with other does since then, but she's going on her 3rd try... I dont know what the answer is either. I'll be watching for advice. Hope you find answers.

Overweight would be my guess in my experience. They can be very hard to get pregnant when overweight.
I know you don't seem to have problems with the bucks and does together but there could be problems down the road. for example: If the Doe gets bred 3 days in a row she will be at 3 different gestation periods which will often kill not only the kits but the Doe. Regulating breeding is impossible as you never know when for sure they were bred and when to give a nest box to them. Even dominant Does get bred when we least want them to. Put her on a diet and try again soon. Good luck to you.

Good news guys. I placed her on a diet and she appears to now be pregnant. She's complaining when the buck approaches, making all the right noises etc. He became rather upset at her change in behaviour. Even when he approached her to simply groom she would grunt and hop away, so we've been giving him a load of fusses and moved her outside again into a wire bottomed hutch on her own so that she can have her privacy. Her mate has been pining in the house, but what can you do? Gave him some new toys to cheer him up a bit.
I appear to have another doe showing signs of pregnancy to, so she has also been moved over to a wire bottomed hutch away from the large buck.
We have two bucks here, a mini lop and a giant mutt lop. We are hoping that the mini can be castrated next year so he can be introduced to the does without the risk of litters.
We upgraded to the larger buck, although I must say the mini lops offspring have grown larger than I was expecting and they still are not fully grown yet (around 8 months.)
Thanks for all your advice everyone.
I guess she was just too fat...

And we have 6 beautiful babies. Her last litter was 5.

Awesome, thanks for the update!