Depression? really don't think.. may help if I get some stories; feed back?

I feel tired a lot. I don't feel like I hate my life or anything but I'm just tired. I am single mom, 2 kids not much family and I work 5 hrs every evening. My doctor said this may be why. I went to see a natualpath and turns out I am allergic to CANE sugar and intolerant to dairy. So I have changed my diet mind you; you cant stay away from such things easy its in EVERYTHING. So I did at first and felt better. I take the vitamins but im tired again. What is it? Guess the question is kinda out there to feed back to similar situations? or just thoughts about depression, or whatnot. I really am a motivated person. I like to read etc. I find time for myself. all that goods BUT I do it TIRED... is this normal ha haa ex; Id like to take up a study but find i cant concentrate and actually take in the information so I stopped going to school (too much on the plate) but i feel this desire to do more all the time.. oh someone a story for me plz.