I've been fat and dieting since I was 5

I'm 20 years old and I weight 94 kg, with a height of 1.74 m. As a little child I was very thin, my mom had to force me to eat..well, at least until I turned 5 and had appendicectomy. After the surgery I started to eat a lot, and gain a lot of weight. I was in a very bad shape even as a kid, because I was always studying instead of playing outside. And even when I was playing with other children I always felt embarrassed because I couldn't run or throw a ball properly.
In my early years as a teenager I had been diagnosed with hypothyroidism. I followed a treatment, been on a diet and even exercised for a couple of months. It helped me a lot for not only the cyst on my thyroid disappeared, but I went to high school weighing 70 kg/173 cm. I was looking better than ever! I had a strong confidence, I wore pretty clothes, and everything was going great.
I don't know what happened after the second year of highschool, but I started to gain weight again. It was a 2 year process so I hadn't really noticed until I got to 90 kg. After I've finished high school I started to use birth control pills for hormonal purpose. It was only a matter of time until I got to 95 kg.
In highschool I used to diet a lot, I even used to starve myself to lose a few kg. When I was a child, my mother used to tell me all the time to eat less, not eat this or that. Well, she still does when I'm between diets. But that didn't help much. I've been to doctors twice since the big weight, but all my blood tests were good. I've been on and off diets lately, and oscillated between 85-97 kg. I even did gym training with a personal trainer a few months last year but no success. Not a single gram lost. But it helped me get in shape.
Now I've moved to England and saw it as an opportunity for a lifestyle change. I've started to count calories, do exercise at home, and even walk 8 km almost every day. I want to go running, but my knees are a bit weak from all the weight I've carried. I promised myself I will go for a run when I reach 80 kg.