5 years later and still trying to lose the last 50 pounds that I gained while pregnant

I am very aware that as a type 1 diabetic I have achieved the greatest accomplishment , because I was able to achieve a fullterm pregnancy . My daughters name is Jenna faith and she is 4 years old and absolutely perfect just because she is all mine ! Going back to before I had become pregnant with her I was 26 years old and because I am 5"9 I look perfect at 160 pounds and that is exactly what I weighed back then …within the first 2 months of my pregnancy I had already gained40 pounds and by the end I was up to 257 pounds which is a 100 pound weight gain within only 9 months…well it is now 5 years later and thankfully I have lost 50 of those pounds threw exercise , and a million different diets, …as of the present day I am still stuck with this exta weight and I exercise 3to 4 times a week and I try to stay under at about 1600 calories a day and I cannot even lose 5 pounds my body seems to want to just maintain this weight …is this a problem that I should be going threw just because I had a baby? I believe that if I wasn’t a type 1 diabetic this would not be my reality …just in case anyone is wondering why I blame this on the fact that I am diabetic is because when I was pregnant I had a basil rate of 7.0 an hour with a total of 200 units by the end of the day and I have read about the fact that insulin is a fat storing hormone and I was not taken that much insulin because I was eating to much it was because when a diabetic becomes pregnant we become insulin resistant…is their anyone out their with a similiar story please share…