If the moment you get money you have to go buy smokes and a freezer burrito, you've crossed into addiction territory. This can kill you, it killed my mother it almost killed me, but it's not too late to save yourself. You don't have to live this way.
What always pisses me off is that if you want to be fat, fine, be fat. No one can tell you what to do with your own body. It's not my place to judge you.
But the moment someone opens their mouths and blames everyone else for their problem I lose my everloving shit. You don't have to eat that food. You don't have to sit around the house. If you have a problem with compulsive overeating you can go to therapy or find an online group to help you confront your compulsive behavior, you can choose to do something different and be kind to yourself.
I don't say this as a fat-hater bastard, either. At my worst I weighed 400lbs and it was awful. I smoked two packs of cigarettes each day, I ate, and I ate, and I ate. It didn't just happen overnight, it took a good ten years of that shit to really catch up with me. That was 2 years ago, now I'm well below 300lbs and I'm really starting to feel like I have a handle on so many things in my life - but I couldn't have done that if I didn't recognize that I had a real problem and needed help to tackle it.
Maybe you've had some serious trauma in your life, but it's time to overcome it. Eating yourself into an early grave and keeping yourself hidden away is not the way to deal.
You can choose not to eat unhealthy foods that come into your home, you don't need a gym membership to lose weight and become more active, and you don't have to just bike to work. There's 8 hours a day where we're usually free to do whatever we want, activity can happen in that time. These are all excuses to keep you in a state of learned helplessness, to avoid life, and to a smaller extent to make yourself the center of attention. It's a cry for help, I get it.
From everything you've said, you know you have a problem and you know you're unhappy, but unless you take action to fix it you're going to be in for a very bad motherfucking time. You are not a number on a scale, and you are not the food on your plate. You deserve better stranger, don't do this to yourself. Go get some help, life can be so much better.
Good luck.