Is it normal to be THIS tired all the time?

I have been exhausted lately, and I haven't really even hit the upswing of this spring's training plan. My weekly schedule is as follows:

Monday - REST
Tuesday - 3 mile run, powerlift (mostly arms) 1 hour
Wednesday - 3 mile run, kickboxing (1 hr)
Thursday - 6 mile run
Friday - Zumba (I know, I could rest, but the class I'm taking is so laid back that it really just loosens up all the tight muscles before my weekend runs)
Saturday - Variable, but speed workout - last week was 6 miles
Sunday - Variable long run - last week was 11 miles

My weekly runs are at a comfortable pace (somewhere between 10 and 11 min/mile) and my long runs are at my marathon goal pace of 11 min/mile. I ONLY do speed runs on Saturday and they are usually around 9 min/mile.

I chose to do powerlift and kickboxing to strengthen my arms and core. I need to get ready for my fall triathlon and without access to a pool until summer, I'm trying to get a strength base so its easier when I hit the water.

I could literally put my head down on my desk right now and go to sleep... right here at work ... and that isn't good.

All signs point to nutrition but I'm netting 1600 calories a day (I used to net 1400). So on days where I have hard workouts, I'm taking in roughly 2600 calories and burning 1000. I'm trying to lose some weight, which is why I'm sticking to the lower intake. But I get most of my calories from protein and am making sure I'm eating a balanced diet.

Maybe I'm getting sick? Ugh, its always something :/