I don't have any kids, but I used to work at a place that was 3rd shift with numerous but sporadic double shifts.. sometimes a full 16, sometimes just an hour or so, but I never knew when it was coming or for how long... and my man was a 1st shift guy.. needless to say I was usually exhausted after a 60hr or more week, and when we did see each other I was certainly not interested in sex...
I totally agree with Jennifer. If your wife can have some "me time" to herself every day (or almost every day anyway) she'll probably feel much more refreshed. Whether it's a walk, a workout, yoga, meditation, a nap, a bath, a massage or spa day (this is a great gift by the way) video game, anything... just sometime when there's no other chores or tasks to be done, and you and the baby are not a concern for her. (Also good to mention, this is great bonding time for you and the little guy.)
After some relaxing, brain and body resting time she just may have some more energy to do the things we love to do ;) This would also help her wandering mind... I know what she's feeling "Oh man, is this done yet? I need to do the laundry, gotta get the dishes done. Oh and I still need to vacuum.... is he finished yet? I gotta get dinner started..." And it's not your fault, just part of life... I'm not saying you don't help around the house (I don't know you ;)) but maybe you can help out a little more by taking an additional task or two each day... to help lighten her load. Or...I don't know your financial situation, but a nanny or house keeper could be a sex-life-saver. Or even a neighbor kid who can babysit for a few hours after school or something...
Was she ever interested in foreplay and oral? Did she formerly shave or trim up her pubic hair? If no, then this will be something you'd just have to explore... but if she used to and after the baby was born she lost interest... well that's a different story.
When she's recharged her batteries, as Jennifer says, she'll be more likely to return to former behaviors and be open to new ones. Do you shave or trim? It's not fair to expect something from our mate that we ourselves do not do.
It's great to hear you want to get her off and that is a priority for you. Keep that attitude!
Now, if all of these things don't work, I'll tell you what worked for me... before I quit that wretched job..lol. I knew I couldn't do it alone. There was nothing wrong with my relationship except for me... my fiancée (then boyfriend) was not doing anything wrong and he was just as wonderful as ever... so I went to therapy myself (did not need couple's.. and I don't feel you do either) I actually went to a hypnotherapist that my doctor recommended. That hour once or twice a week was wonderful.. talk about getting a recharge. Not to mention the tools one can be given to fix their mental and emotional issues while working with a qualified therapist... It truly was amazing. One of the main issues I told him about was my total lack of sex drive (I mean total)... Within 2 visits focusing on that I was back to my normal self. I don't bawlk like a chicken when a bell rings or anything weird like that... it may be something worth looking into. Oh, and the weekly massage I got was also heavenly.. more for relaxing and letting go of tension than wanting sex.. but it all works together. :)
Good luck. I hope you can help your wife return to a healthy sex life.. even with the little guy it's quite possible to have sex regularly.. you just have to be careful ;)
Oh, I forgot... is there any way you can get a set schedule at work?