I have a question for married mothers.. please need your advice and views...?

Hi, well here it goes. I am 26 years old married for a year now and we have a son about to be 1 year old. Me and my hubby were dating for about a year before we tied the knot.. anyhow.. im a working mom and my jobs very demanding.. anyway when I get home, the nanny leaves, so, I play with baby, feed and put him off to bed then clear off all the toys and then prepare dinner.. this basically is my everyday life, and I am totally used to it and love being a mom.. Problem is that I feel that I get soo tired working and being a mom that I am slowly falling out in terms of being an "intimate wife", when hubby wants to have sex, I have the interest but am soo tired and basically fall asleep.. I feel that it is affecting our marriage though we know that sex is not important but hey it is a very intimate part of marrige.. right?? we both love our son dearly and love each other deeply... mothers please give me advice on how I can make things spicy and romantic despite me working and being a mommy and managing home...