Oh, Ruth. I'm sorry. I don't know what you should do. I guess we're trained to look to doctors for answers on how to deal with health issues. Well, you saw a nutritionist. How about your doctor?
Then, it's most probably the difference of the lab and test equipment. This stress is adding to more stress for you. Maybe it would be better for you not to even test yourself for awhile and just eat your diet that you know is good plus more calories to add some weight?
I agree that her readings may not be accurate. I have anxiety disorder, and I'm in the middle of a VERY stressful 12 week training at work right now (which is why I haven't been around very much during the weekdays... so tired... ). If stress makes our numbers go up that much, mine would be through the roof! I've been sticking to my diet faithfully, even at work, passing up the pizza and donuts they've given out. The only time my readings are a bit high is in the morning, because I'm too exhausted to have a snack before bed (I think ). I'll bet your reading at the doctor's will be much better...