The hypotheses I can make, quickly, like that...
-Thyroid gland issues
-Your testosterone has lowered (but if you have the slightest of transgender issues, this should make you feel better, not worse, if you're like me)
-The beginning of a burn-out / the urgent need of taking a vacation (with your rhythm of life, it wouldn't surprise me one bit)
-Stress accummulation
-Depression or similar issue
-Bipolar/borderline disorder (I always forget the difference and which is which) starting to manifest more of its down side. That should have happened and be diagnosed earlier, but who knows.
-Your efforts to lose weight have lowered your metabolism, making you burn less energy, thus tiring you.
-Diabetes (though really, you would've noticed the difference, wouldn't you?)
-Hyper/hypotension (high or low blood pressure)
-You're just getting older. I think it's not so abnormal for energy to go down suddenly.
-Lack of physical activity
-Symptoms of coming off nicotine
-Way, way too much coffee (I converted it and I was like "whaaaaaa, 1 L of coffee?! Isn't she dehydrated?! - How about trying green tea? It tastes great (to me), has less caffeine but has a less "burst-ish" kind of caffeine that has a more long-term effect, on top of having tons of benefits, especially if you drink a lot of it)
-Lack of sunlight (it's been proved to cause symptoms, including seasonal depression for example - but use sunscreen, because UV rays are nasty!)
I would really recommend meeting with a doctor. You don't have to tell them about your gender issues if you don't want to, and they will have alternate solutions if they think you should take antidepressants but you don't want to.
Also, uhm... Do you have such a low salary? Or are doctors so expensive in the US? Because with the insane amounts of work you sound like you're doing, I think you'd likely have enough money even with a low salary... But well, we're talking about the US here, where not much is logical or right. ^^'
Anyway, if price is really too much of a barrier, you can look for free, not-so-perfect-but-useful alternatives, such as:
-"Ask a doctor" forums
-Your pharmacist, who can give free, reliable health advice if you ask. You can even meet them in an office if you'd like. Well, here you can, anyway. If you're shy for a face-to-face meeting, call the pharmacy and ask to talk to them. It's anonymous that way.
-Free "info health" phone lines. I don't know if you have something like this, but here, if you dial 811, you can talk to a nurse who will give you professional advice on any health issue you might experiment. See if you have something like this around you.
I've also heard of doctors who run "charity" clinics where they see patients for a fraction of the usual price, or charge them depending on their income. Look it up.