I also had five stone to lose, am now nearly a stone down and have got there by calorie counting - my limit is 2000 but most days I hit around 1800. I don't know if it's the psychology but having a generous limit has made me be consistent for a month. I tried 1200 limits in the past and would inevitably fail very quickly - I'd feel like I ruined it if I went to 1300 and then throw in the towel with a binge.
I'm not tall, 5ft 3, so this sounds like a lot of calories.When the losses stop I will cut it a bit further or up the intensity of my exercise. I don't overcomplicate things with fasting, eliminating food groups etc - I eat normal food. When you are that overweight, there is no need to make it super sophisticated - you simply need to start with not consuming too many calories.
I'm not sporty but I move a lot - I naturally walk an average of 15000 steps a day and I've been making an effort to do small things like take the stairs, stand up on the train, walk around when looking at my phone or whatever . Making activity part of your daily life will do more benefit than a punishing fitness regime that you'll ditch the first time you can't be bothered to go to the gym. Find activity that you enjoy and can realistically fit into your life.
I have started lifting as well, it's surprising how much it raises your heart rate and will make your body change quite quickly. I enjoy it and hopefully as I lose more fat it will reveal a strong and capable body underneath. Have goals other than "I want to weigh less" - why? Do you want to be able to wear nicer clothes? Feel more attractive? Be able to climb four flights of stairs without feeling like you're going to die? Don't fixate on the scale number as a goal itself , just see it as a guide for how you are moving towards other types of goal. I also totally agree with smaller steps - even if you look at it as 1lb at a time.
There are no magic bullets. Medical intervention may assist, but won't cure it and if you stop without changing your behaviour, you will go back to being overweight. If you accept that it will take a long time, it gets easier. I also found being kind to myself has helped a lot. Being overweight is not a moral failing.
I found James Smith's book really helpful. There is so much good free content out there on social media if you find it wisely - James Smith, Ben Carpenter, David Birtwistle... They all talk complete sense.