I agree that the ideal weight thing is a load of old tosh, largely, and it's what you feel comfortable with.
However, if you were eating 2000+ cals per day and not gaining several lbs per month, especially not exercising (bear in mind Northerner ran marathons) then I would be looking to other causes and the favourite for any T1 is less than perfect control.
Stress will play a part with weight as well as the higher BGs you spoke about in your earlier thread, but generally calories in minus calories out will equate to weight loss or gain. To burn 2500 to 3000 calories a day, you have to spend the day running round or peeing out the excess glucose due to high BGs. Or something else, such as a thyroid problem.
But testing several times a day before meals, 1-2 hours after meals and bedtime & morning, for a few days, should highlight if you have any problems with highs. It would get you a sub-7 HbA1c and your overall health would be far better for it. 🙂
Rob