Am I not eating enough or am I just tired?

I guess my brain is just not functioning lately, so I need somebody else's insight or experience.

Ok, so my office has moved and I'm now walking pretty much double what I was. So now I'm walking 20 minutes (uphill) to work and 20 minutes (downhill) from work. I've got my activity level set to lightly active so assuming I want to lose 1 pound a week, I'm supposed to eat just under 2,000 calories (~1,990 cals). I will also log my runs when I do them and only eat back the calories burned from the run (never from the walk since I assume that is part of the lightly active calculation). Problem is that the past few days I've been feeling really tired but not much of a desire to eat anything far beyond my calories for the day and I'm not really hungry. I drink water like nobody's business (usually around 8-9 cups by the end of the day) and I know I'm not dehydrated. But man, those runs have been murder the past few days. I restarted C25K and thought maybe I was going to fast so took some extra rest days and am still feeling like crap. I sleep 8-9 hours a night but lately I've not been sleeping as well due to some pretty bad nightmares that leave my heart racing and keep me from getting back to sleep for a while.

So I guess I'm trying to figure out if I'm not eating enough or if I'm tired or if somebody has some other idea of what the heck is going on. (Which reminds me, thyroid has been checked and its fine)

I'm 5'11" female, 224 pounds, 28 yrs old. I've lost 7 pounds since starting at the beginning of June (god bless the food scale!), but something is making me feel "off" and I'm not sure what. Hoping for some insight here.