Hi and
I'd recommend you start walking. Maybe only a few minutes to start, but start working your way up. Walking is so good for you, requires no gear, and will really help you prepare for an active career. Maybe get a pedometer (your phone may be able to track this) and work on 10,000 steps per day. Make that a requirement before you can do something you like (for instance games).
Maybe don't even weigh right away. Pick something that fits you right now, and make that your measuring tape. Get your walking in for 2 weeks, and then test that garment again. I'm sure you'll see results.
I also recommend food tracking. I like myfitnesspal, but there are lots of 'em. You'll probably find you are eating more than you think (we all do it). Once you track for a while you will start to see where your problems are.
Good luck with your journey!