I have a complicated dietary problem need advic?see details?

I had severe anorexia at the age of 19 and starved myself
down to 134 pounds at the time from a obese weight of 330 pounds

I started eating normally again and kept my calories at 1600-1800
per day but my weight balooned.I was a vegan,and no matter how
I restricted food and calories I kept gaining more and more weight
it has been 7 yrs and I am obese,sick and have digestive problems
Every time I eat my blood sugar crashes,I only eat gluten free food
brown rice,beans,olive oil,fruits and no sugar,im allergic to soy
nuts,eggs,peas and several legumes.It has been suggested to me
by a doctor that I have insulin resistane and PCOS,and that I should
be on a low carbohydrate diet.But everytime I START IT im not used
to eating meats,and my blood sugar crashes all the time.The funny
thing is when I EAT carbs even brown rice with beans my blood sugar
drops and I get reactive hypoglycemia and pee all day,feel shakey,
jittery and get heart palpitations.I am suffering from IBS and havent
had a normal bowl movement in years I have diarrhea every time I eat.

How can I keep my blood sugar from crashing on a low carb diet?
I feel so sad because though I am obese I havent been able to eat
or enjoy food due to allergies…..SOMEONE PLZ HELP ME
MY DOCTOR SAYS I MUST LOOSE WEIGHT BUT HOW??I
HAVE TRIED,I FEEL SICK AND TIRED AFTER EATING I HAVE
CFIDS CHRONIC FATIGUE AND LOW THYROID!

Hazel