I'd second the low (or at least lowish) carb suggestion. Unfortunately high blood sugars plus lots of insulin results in weight gain, so the only way I've found to keep mine under control is to keep my basal as low as possible, which means exercise plus not too many carbs. It's unfortunately a common symptom of T1 diabetes. But whatever you do don't go the diabulimia route (skip insulin to lose weight). It's better to carry a few extra kilos and keep normal blood sugars than to lose weight and risk DKA plus diabetic complications.
Good luck.
ps I'm guessing weight watchers are low fat high carb? I'd recommend the T2 LCHF route, high carbs lead to excess insulin leads to weight gain....