Welcome to the forum!!
Don't worry about how much you are going to lose... just get started!
Whatever you end up weighing in a year, will be less than you are now and you will be healthier and more energetic to boot!
Open a journal..to track all your progress and you will be amazed at all the changes that you make on this weightloss journey.
Please don't see this way of eating.. as a diet..or a quick way to lose weight, you really need to commit to this being a longterm, life plan..then you will never again have to worry about your weight.
Others have lost that much weight in a year and kept it off!!
All things are possible, depending on your commitment and determination.
I look forward to hearing of your success.