Hi NikNak,
I lost just over 10st - it took me 4 years and still have a tiny bit more to go but I got there!
I am T2 on met and gliclizide so I may eat a little different to you but here's how I did it it may help
I stuck to 1400 cals, between 90 - 120g carbs ( as a T1 this may be too low for you that's for you to decide)
I record EVERYTHING I eat on myfitnesspal - it gives you all the nutrition info you need and you can record your weight loss exercise etc.
I never looked at the big picture, instead I set a small goal like I want to be 5lb lighter for my birthday in 4 weeks,once I got there I set another, this seemed to me to be more achievable. I only get weighed once a month and was always lighter than the month before
One rule I set myself is that if I wanted to eat I had to set the table and sit at the table to eat it, even a bit of chocolate, this soon stops you snacking as it just isn't worth it :lol:
Good luck you can do it think positive and if you slip up don't punish yourself, but get right back on, not oh I had this today so it's messed today up I will get back to it tomorrow , get back to it straight away!