Hi Alicefalling
I just want to say big hugs - I know how you're feeling - I think actually in this respect we're pretty similar. I am also 5ft 4 - and was over 12st. I am happy to say that over the course of about 6 months I lost 22-24lbs and am now a healthy weight for my BMI and i feel so much better in myself. And not just because I lost the weight but because I changed my lifestyle and I couldn't go back to the way I was before, now.
I lost it about 18 months ago now. I got married and before we were married we were perfectly happy. After getting married although nothing changed on the outside (we were already living together) something changed on the inside and we weren't happy for quite a while. I piled on the weight. I think it took hitting rock bottom in the relationship and some external things - for me to feel like, although I couldn't control anything else - I needed to take control of my life.
I too had tried weight watchers, slimming world, slim fast etc - but weirdly it was the special k diet that got me on the right road. Nothing in particular about the diet - you don't need that one specially - but because I had to weigh the cereal - it made me realise that my portions were about double what they should be. I lost 6lbs in 2 weeks on that diet. Went on holiday and put it back on! But I remembered the lesson.
And then a couple of months later I joined the gym and because I was unhappy it made me determined to go. I also started weighing all my food and making it all myself rather than buying ready made stuff with all sorts of stuff in it! This way I could control what I was eating better. I used the spark people website to track what I was eating and my calorie intake which really helped. I didn't ban any foods I just stuck to 1300 - 15000 calories a day, workouts of at least 30 min cardio 3 times a week, and weights at least once a week.
After a couple of months and losing about 1-2lbs a week, I decided to do a 10k run for charity and started training for that. I was absolutely terrified - I'd never run that far before! But i took it slowly - started on 15 minutes on the treadmill, worked up to 20, then 30, then tried 30 mins outdoors - and before I knew it I was running 10k. And the goal kept me going, kept me going to the gym, kept me running.
And I did the run a few months later - and then before I realised it, I'd been eating better, and doing regular exercise for 6 months and had lost 22lbs. I even went on holiday afterwards and despite eating what I wanted and drinking - I didn't put much on, just a couple of lbs. Because my stomach had shrunk and I could no longer eat what I used to eat - so I don't need to weigh things as much now (I do still do it with things like pasta as I can never tell!).
I know - this is insanely long post! But i wanted to tell you my story because I think I was in a similar place to you, with a similar issue and it can be done - give yourself manageable goals - don't expect miracles - don't beat yourself up if you can't make the gym all the time, or you scoff a load of chocolate- just make it up the next day or week. Just keep going - and what really helped was imagining myself in this pair of hotpants I had that I'd not worn in years - I put them on before I started - took a good mental picture of it all, imagined myself how I wanted to look in them and every time I felt like giving up - I took out my mental hotpant pictures and it made me keep going!
And now - I still run regularly, go to the gym regularly and manage my portions and I've stayed the same weight more or less (yes it goes up and down a bit but thats to be expected and I don't beat myself up about it - that's important for me or I get disheartened) and I'm happy. And I'm happy to say that my husband and I have somehow made it through our issues and are now happy (although that had nothing to do with me losing weight, except perhaps I regained my confidence and self belief which helped).
Good luck. You don't need diet plans - do what feels right for you. Give yourself regular treats and realistic goals, don't beat yourself up when it doesn't go to plan, and keep visualising your intended achievements. It does actually really work!