Hi OP, I'm in the same situation. We have a part-time nanny who takes care of 1 child for us. We pay her $17/hour before tax for up to 30 hours. With OT at 1.5x pay, she would be making $19 to $22/hour on average, not counting paid leave and bonuses.
We were going to transition to full time in 2017 with OT, paid leave, paid holidays (she gets this now), year end bonus (she will get this at the end of Dec even though it will have only been 2.5 months), paid vacation, etc.
After being with us for less than 2 months, she is asking for a VERY substantial raise. I wish she would have said something when we offered her the job because there were a number of others who were interested in the position for the same compensation. I don't think she's doing this because she thinks she has us over a barrel--I think she genuinely didn't think through how much the pay would be, compared to what she was used to. We just can't afford what she's asking.
I've offered to join a nanny share so that we can substantially increase her pay, but she wasn't interested. Instead, I'll have to find an alternative for our child. I told her I'd help her find placement with another family, but I don't know how long it will take for her to find someone at the rate she seeks.
Can I get a reality check from all the MBs and nannies out there? 2 months seems to be a short time to be asking for a raise. Also, isn't it hard to find nanny share level pay/multiple children level pay for taking care of 1 child? I don't know how I'll find her something like this.