To be honest, it sounds highly likely that she is just having a phantom pregnancy. My old dutch girl dug a burrow in my garden, lined it with fur and and hay, then filled it in again. Nesting is common in unspayed does.

My last dutch girly used to nest every few weeks. Sadly we lost her at 8 months before i could get her spayed. My current Old English hasnt nested yet, but she constantly humps her neutered male companion. It seems to be a behaviour that can increase with age. My original dutch female did it constantly, right up until she was 9 years old.

Rabbits often exhibit behaviours we interpret as meaning something they dont. Nesting doesnt always mean the iminent arrival of kits. Im not saying she isnt pregnant of course, and i would advise, like others, you get her vet checked asap.