"Physical work" does not equal massive amounts of weight loss. In fact like I said, it is possible that it could contribute to weight gain if your body is manufacturing lots of cortisol in response to stress. Look around at manual laborers such as landscapers, road crews, and construction workers--they tend to be on the pudgy side more often than not, and they certainly work their butts off. In fact they are usually more overweight than upper-income workers whose jobs are not physical in the least. I'm not saying that you don't work hard, not at all, but to lose weight consistently through exertion it has to be something cardiovascular, something that causes you to get out of breath some. Very few jobs consist of sustained cardiovascular exercise and therefore you need to incorporate it into your life some other way.
The reason you feel like crap all the time is because living at a severe calorie deficit for long stretches just is not healthy in any way. Just because the human system is able to do it doesn't mean that it's good for it to do it on a daily basis. Your body does not have the energy to take care of its daily needs and having lost 80 pounds in five months is extreme. Your body is likely already in starvation mode, thinking you might not eat well for another three years, and is in maximum calorie conservation, and you are more vulnerable to all kinds of illnesses (not to mention deficiencies) because your immune system doesn't have the building blocks it requires. Most professionals would want that amount of weight loss spread over three years. Also, another thing to consider is that rapid weight loss frequently involves quite a bit of dehydration because a lot of it is fluid loss, and puts you at a high risk for developing gallstones which is an emergency. That's terrible for your kidneys. From everything that you are writing, I'm starting to become concerned that you are developing an eating disorder and that's very bad, as all of us know.
I think you need some professional consultation and input but here is my advice for a healthier way to lose weight in order of what I think is best:
1: Cardiovascular exercise--something sufficient to make you huff and puff to some degree for a minimum of a half hour a day. This could be:
a--running
b--vigorous walking or hiking, especially if uphill
c--treadmill
d--dance
e--martial arts
2: Healthier food items, particularly removing trans fat completely from your diet as well as excessive added salt and sugar. Only whole-wheat carbohydrate sources. This does not include artificial sweeteners, or cutting out all animal fats.
3: Having a big, filling meal when you eat and no snacking during the day
4: SENSIBLE caloric reduction, meaning 1800 calories a day, not 1200