Nutrition frustrations and confustion

What does it mean when your nutritionist says that your situation is puzzling?

Hear is what happened. Three experts say that I am under eating. I agree that I should be able to eat more. Testing revealed that my resting metabolism rate was quite low. Solution, eat more. Your body is smart and will figure it out. Testing shows how many calories are burned at specific heart rates on the bike. That plus the RMR plus a little extra for not staying in bed all day equals the calories that I can eat. Good.

RMR + living + exercise = Allowed

On paper, this all makes sense, however, I gained weight pretty continuously on this even though I was an average of 250 calories or so under that amount. However, the rate that I gained corresponded with the amount extra that I was eating. I had been eating about 1200 calories per day on average. I changed to eating about 1850 calories per day.

(1850-1200) * 28 days = 18200
18200/3500 (one pound) = 5.2 pounds

And yes, that's very close to what I have gained.

Why would I be so special that time tested formulas wouldn't work?

We know from bloodwork that at 152 beats per minute on the bike I burn 9.2 calories per minute which works out to 552/hour. We know from testing what my RMR is, this was not a guess. Even if you give me 0 calories per day for not laying in bed, this still does not work out. What is going on here?

At the same time, I am further away from my weight and body fat targets than I was four weeks ago. Frustrating. Very frustrating.

Maybe four weeks isn't a very long time for my body to adjust?

I need to give myself better gifts.