Okay so a little background:
I'm female
Age 21
Slightly overweight

I've had Interstitial Cystitis since I was 14 - not a big issue there.

I have had issues with depression in the past - never enough to talk to my doctor about, but just putting that out there.

It is currently Feb. 17 2011 - since probably about July 2010 or around there I have been feeling extremely tired all the time. Whereas before that I would sleep maybe 3 hours a day and feel fine the rest of the day - I was always a purpose driven person and it always seemed fine as I either had school or work.

From July onward I've slowly been feeling more and more tired - at first I thought it was because I had a bladder infection at the time - that went away - my tiredness didn't. Then last fall, I was a bit depressed - as I was almost done with college but was having trouble finding a job and there were some family issues. Then the tiredness was still persistent but manageable. In December I finished school - still not able to find a job. January came - sent out a lot of applications more or less waiting to hear back on stuff at this point. But I would say from the beginning of January until now my tiredness has increased - at this point I spend more time asleep during the day then I am awake. I feel kind of worthless - but otherwise the actual depression seems gone - at this point I essentially feel nothing good or bad. On top of the tiredness I keep getting pains in my lower back, but I'm not sure if they are connected. In late January I joined a gym but I haven't overly stressed myself there so I don't think that the back pain is from there.

Right now I just want to feel normal again - to have energy again. To feel like me again... Course I've actually tried calling my doctor about it and she's been out the past two weeks and isn't expected back until Tuesday - and her nurse isn't there either. When I've asked to talk to another nurse the receptionist just asks if she can take a message - I just said I'd wait till Tuesday.

Most responses will center on your depression, and that certainly makes sense.
But I'm not so sure it's the whole story. I too am more tired than usual, ever since an infection (cellulitis) last summer. I have a friend who has had recurring bladder infections and got tired a lot. Trying to research all this gets murky pretty fast. There's the effects antibiotics have, but there's also a sense that bacterial infections can have residual effects that MDs don't really pay attention to. I have pain around the area where the cellulitis started, and 2 doctors could not tell me why. 'It happens' they said.
There's a lot more attention to Lyme disease, which can leave you with bouts of tiredness and/or severe arthritis. It is caused by bacteria other than strep or staph, the most common, but they are all bacteria, they can get into the body past your skin (where they can reside normally), and SUPPOSEDLY once you finish a course or two of antibiotics, and there is no fever and no skin rash and nothing showing in tests, you have nothing to complain about. Many of us don't believe this for a second.
Some people subscribe to the idea that more antibiotics are needed, preferably IV.
Others say that once you get any internal inflammation/infection, changes take place in your joints and muscles and tissues that are similar to the mysteries of arthritis and aging. This is what doctors sort of shrug about.
Being overweight means people will tell you to lose.
Being depressed means people will tell you to get help for that.
Taking antibiotics means you need to get your flora back with yogurt and healthy foods. (I think I am far more fatigued by sugar than before, and also possibly am now allergic to gluten. I just don't know.)