Thyroid? Diabetes? Birth Control Pill??

I went on the Pill when I was 17. My weight was 130lbs my height is 5'1''. I was no more active then, then I am now. I gained approximately 60lbs and the doctors kept saying it was not the pill. I am now in my thirties and my weight is now 275 after two kids. Here is where my medical history gets weird. I got pregnant I had not had a period in four years ( I stopped taking the pill when I was nineteen and since then no period) I miscarried and after that still no period. I got pregnant 3 months after the miscarriage and my first son was born. After him no period; lots of Doctor appointment to see why my weight was still rising and why no period. Checked me out for thyroid and diabetes nothing to indicate that I had either condition. Four years of appointment and my weight was still climbing. One doctor decided to put me on the pill again for 3 months to see if it would bring back my period. It did and my period was regular for about 6 months when I found out I was pregnant again. My second son was born, this time ( the doctor said it was because of my weight) I was Gestational Diabetic, controlled by diet. My second son is now a year old and I have had only one period since I stopped nursing and that was two months ago. The doctors can't seem to find a reason for it. I don't want to have to go the pill again. My weight has not changed in a year and I fear that if I go on the pill I will surpass the 300lbs mark and I want the weight off not more. Thyroid runs in my family, several family members have it. Does anyone have any ideas as to what is going on? Why is my body not working?? Am I going into early menopause?? What should thyroid levels be at to be correct. I know that I am not diabetic because I check my blood sugar with the glucose meter I used when I was pregnant. And my levels are always within the normal range.