exhausted with a capital E

I am SO TIRED. and I don't know why. I think i shouldn't be? Because I'm blessed with a baby who sleeps through the night since 11 weeks. Work wise, i have had increased work load, but I think it is still manageable as a whole? And I've also resumed working 1-2 saturdays a month. Hmm. Study wise, it's done! Ministry wise, I'm only coping with once a month serving at most. Breastfeeding wise, I'm only pumping 4 times a day now (verses 6 times a day previously). So why I am tired everyday? I have no mood and enthusiam for anything. can't figure it out :( I just want to sleep and have a good long break. Yet I cannot bear to be apart from my baby. Not even a night :( And I've not put in any effort in weaning her to formula milk. But I know bfing is not sustainable for long. it takes A LOT for a working mother to cope. so anyway, my point is, I AM SO TIRED AND I DON'T KNOW WHY.