I could have written your post except I weight 87kg at age 11 when we had class weigh ins and most of my classmates were around 40kg
I started my journey at 125kg after an entire lifetime of being overweight (well, I was a normal weight baby to be fair).
The first thing I can say is that you can do it. I can be really flaky and RARELY stick to anything but something about seeing my highest weight of the scale made me realize that I couldn't not do this, whatever it took. I white-knuckled it on my own at first... setting my calories low and lost like 17lbs. Then I found 3FC and that made my journey so much easier- all the support and information and challenges kept me motivated and on track.
I set my goal to lose 50 kg and believe me, to me it was crazy numbers. At that time, my dream was to be a US size 12. But that didn't stop me. I set mini-goals, I joined 5-lb challenges, 2 week challenges, all sorts of things that would keep me motivated. 50 kg might seem a lot but setting a goal and taking it 1 kg or 2 kg at a time made it a lot more doable.
Also it took a while, but I got to the point where I decided I wasn't in a hurry. Sometimes, i got bored or tired and I allowed myself to go into phases of maintenance, eating more but still weighing regularly to ensure I wasn't re-gaining. My plan was calorie counting and 55kg later, I still calorie count. I don't restrict any food groups and I have treats from time to time. The main things to realize are this isn't a race, you're not in a competition with anyone, this is a marathon journey, time will pass whether you act or not AND that you don't have to be perfect at this all the time, just most of the time. You can totally do it!