If you aren't eating enough calories each day, you will feel sluggish and ill. Your body has to have so many calories/day just to function and if you don't provide them, it will only get worse. I don't understand your bp reading; do you mean 80/60?
If you aren't eating enough meat or other foods with both iron and vitamin B12, you could be anemic. You should get both an iron panel and a vitamin B12 test.