I just wanted to let you know you are not alone, although I've gone a different route as I have personal care needs I have a P.A. who is supposed to be supporting my parenting role in September when my baby comes. She won't ever have sole charge but negotiating the relationship is really hard, and we're expected to do this with no management training or experience. In some ways it is easier because the boundries are (supposedly) firmer ie. I am always the parent and she is only there to help me not to provide childcare.
For me I'm not sure a routine would help very much - it's a damn good idea, but due to the nature of my disability it's just not always possible to know what I'm going to be abel to do.
I've had to go about it in more of giving an idea of my capabilities, the ways in which I will/may need assistance and the style of parenting I'd like to approach (pfb so I get to do that 
).
If things arn't working do arrange supervision for your employee - basically write out everything thats annoying you or not working and try to find a solution. Have a meeting and discuss how things arn't working and why and ask your employee if they can think of any solutions that will solve the problem - sometimes their solutions will be better than yours. Always warn them this will be happening (I gave 24 hours notice at the end of a shift so the employee doesn't spend the whole shift worrying about the next day) and ask them to think of things that arn't working well for them (they don't have to bring a ready made solution just the problem, you brainstorm together). You'd be suprised how often it's the same things, even if it's not it makes it feel less onesided and confrontational for you both.
I've definatly found organisation is the key, so set routines for separate tasks if you like, the tasks may change and vary but the routine for each task stays the same. For instance my wetroom isn't levelled properly so towels must be put on the floor, we kept running out of towels, towels were being left wet on the floor and sometimes being put in the basket wet. We now have three designated black towels (no other towels are black) for the floor, once wet they must either be hung up or put straight into the washing machine. No more smelly towels. I also have to wear TED stockings, only have two pairs - so to get a clean pair they must be hand washed everyday, that's DH's job BUT the P.A. is the one who helps me get dressed. Socks kept getting missed (I did keep asking for P.A. to give socks to DH but she just wasn't understanding that meant TO him not just left in sight). At the meeting it was made clear that the socks must be placed in DH's hands - this protects P.A. from getting the blame for lack of socks and DH never forgets if he is handed something, I always have cleans socks and everyone is happy. I try to think of it as a system not working rather than it being the persons fault, if we can perfect the system so everyone knows what they are supposed to do and can follow it things run smoothly.
Also the main thing I looked for was someone who really really understood that things would be done MY WAY! That they throughly understood that no matter how much assistance I ended up needing they were just a physical body to help. It sounds really harsh but my P.A. is fully ready to support me in an attatchment parenting style, it's completly alien to her, but my baby, my rules and she really seems to 'get' that. I have no idea if it will work in practice but we have everything but the parental assistance set up in a way that is least annoying to me (the only way I'd be happy is if I could get rid of her and go back to doing it all myself that is not going to happen though).
As far as the nanny that made you feel uncomfortable I'm afraid we'd have had a supervision about what support I needed from her and why was she feeling unable to provide it, could she think of a solution that meant I would feel supported rather than excluded. Had that not worked I would have moved onto disciplinary procedures, I know it's hard to manage people, I know it's very very hard to find people, but if they arn't doing what you need them to you may as well send your child to a normal childcare provider - it's unacceptable to be made to feel out of place in your own home with your own child.
Sorry that's so long 
I really hope you find someone you can rely on.