She may just be having some irregularity because she's just starting her laying. We had 4 lovely Delaware pullets, and two of them hit the ground running when it came to laying eggs -consistent in size, condition, and delivery - they laid like real champs. The other two dragged their feet, laid a few soft-shelled eggs & nothing more. They were totally rubbish, even stopped laying the soft-shelled ones for like 3 weeks. After that, they cranked up again, laying great just like their sisters & they are still going strong. Sometimes, ovulation (whether chicken or human) is a tricky think in the beginning, and there can be fits and starts. This sounds like what your pullet's going through. Just keep an eye on her for another 3 - 4 weeks, since it may be that her body just needs to catch up.