I've lost 8st so far and another two to go over the last couple of years. Theoretically, it's doable. Average a 500 calorie per day eating deficit and the same again through exercise and you're more than covered. The biggest problem is how you do it and whether it's sustainable. A year is a long time and you're not giving yourself much wiggle room. Especially if you're going down the "going on a diet" routine.
You also need to account for the fact that the more, you lose, the more effort it takes to lose more in the same time. It's easy to see quick gains when you have a lot to loose because your body needs more calories just to exist so creating deficits is easier.
When I started, I decided to put the effort into learning more about the food I was eating. I started to research where I could get the most bang for my calorie buck. In all honesty, I wasn't looking to eat "healthier" right away, I just wanted to stick with eating crap but be smarter with it so I could create those deficits and get some quick wins on the scale. I started to walk more and I've built that up over a year to the point where I'm averaging 10,000 steps a day. That's the only exercise I've really bothered with - although I know there are other things I need to start exploring for other health benefits beyond weight loss.
Over time I started to integrate healthier eating and I focused on changing one habit a month so that, over time, things gradually build into my routine and it didn't feel like such a shock. I'm at the stage where I'm confident that I won't put the weight back on when it's all over because I've been gradually embedding better habits bit by bit and it's never felt like I'm on a diet.
I'm a bit like you, I still factor in treats to give myself a break and it can be easy to go overboard if you have a tendency to binge. The main thing for me was to accept that the journey would be 2 steps forward, one step back because, overall, it's still going in the right direction and it's sustainable.
I think you should really think about the approach your taking and make sure it's right for you. If there is a diet or combination of diets that works for you and you can sustain it long term, that's great. Just make sure you're taking time to learn about food and diet as a whole and now just through the lens of one diet because you really need to plan for what happens after the diet is over. I think you should extend your target, too. I'd maybe go for 18 months rather than a year. The worst thing you can do is set an unrealistic target and then end up undoing your progress because you're losing motivation when the scales aren't where you think they should be.
Good luck and keep up the good work!