Hi Little Kitten and welcome to the forum! The support here is totally give and take with the most wonderful people you will ever want to 'meet'!
As far as working your 12 hour shift and also having a family to care for, as well as keeping in mind your sleep schedule, only you will be able to come up with a suitable MF eating plan designed around your work schedule. Much will depend on how busy the floor is when you are at work.
As someone suggested, the Ready to Drink Shakes are wonderful and can be fit into your nursing schedule--call it "sip and run"!! Trust me, been there! During your waking-working hours, you should try to have a supplement every 2-3 hours to stave off hunger and keep the old metabolism cranking. Again, you might give the Ready to Drinks a try, so convenient, quick and no mess to clean up and easy to get in on an especially busy night.
Good luck with your program, and keep us posted.
Joan