I used to blog for a Sex Educator, so I might be able to help
What are your days off like, OP? Do you guys have more time together then? What was your sex life like before being a nurse?
I know I have more questions than answers so let me settle that!
You and your husband can and should find intimate moments when you can. It may not lead to sex (which can be okay given your schedule); but, it can be foreplay - whether it's a shower together, him giving you a back rub after a long day, etc. I can completely understand being too tired for sex, so try and find other things to do that are brief but encourage intimacy and relaxation.
Make sure you have sexy stuff in your wardrobe too. It may not lead to sex; but you want to keep that sexual intimacy alive and visual cues are essential!
Use the days off to bring sex back into the relationship. Get out of the house and maybe spend a weekend at a hotel or cabin in the woods. Removing yourself from your daily surroundings may help to shake off that nurse mentality.
Maybe a vacation is in order... have you started planning that yet? If you can't help but get into nurse mode when you see him naked, you may need to take a break. He's your lover, not a patient