The reason for the banana is for the slow release when I exercise this afternoon.
I forgot to mention I do not eat any dairy products, fish or eggs.
If you want to lose weight, your aim is to burn body fat for energy. If you keep eating carbohydrate to use for energy then weight loss is likely to be difficult.
I think that you are still following non-diabetic diet guidelines, and "healthy eating".
A lot of people on this forum have found that cutting right back on carbohydrates and increasing the amount of fat eaten has resulted in weight loss.
Further, if you are not losing weight on 1500 calories a day, then reducing the number of calories to, say, 1200 might make a difference.
Please note that calories are only a rough guide - to get energy from fat requires your body to expend more energy than getting energy from carbohydrates. So 100 kcals of carbohydrates is not equivalent to 100 kcals of fat.