You are 16. You do not want a double mastectomy. You don't even know your body yet. You haven't seen your body yet. It isn't finished developing. Your brain wont finish maturing until you're in your 20s. To say that you know right now that you want to make a permanent modification to your body is so rash it is itself proof that you're not mature enough to make such a choice right now.

That probably sounds condescending to you but it's important. The discomfort you have now, it ENDS. It really does, and not long into the future.

The wisdom of my extra decade and a bit has taught me it's crucially important not to fuck with your body any more than you absolutely have to. You are not a Mr Potato head that can have parts added on or removed without consequences. Your body is one interconnected whole. Messing with any one component has flow on effects. Stop binding your chest. Long term use decreases lung capacity and will make the entire rest of your life harder than it should be.

Whats "disgusting" about tits? Are they gangrenous and rotten? Got maggots in them? There's nothing "disgusting" about any part of your body. That is just a thought in your head. You can change that thought any time you want just by deciding to. Decide now that your body is just fine. Hating your body is a waste of life (another lesson I had to learn after I was your age).

whether I am actually a lesbian or I am a guy

Well you can't be a guy, so mystery solved. No one can ever change sex. There's not such thing as being a man "on the inside". While we're at it "gender dysphoria" isn't a real thing either. Being uncomfortable with your body is normal, especially in puberty. Being uncomfortable with the femaleness of your body is so normal it's boring given the society we live in. I don't know ANY woman who was perfectly happy with her body at your age. In my day it was anorexia, bulimia, and cutting. Now it's mastectomies and testosterone. The sooner you change course away from self hate, the better off you'll be. You can never hate yourself into becoming someone that you can love.

I know that I have xx chromosomes (most likely, never actually had them analyzed :0)

If you've even had a period you are 100% for sure a woman. Trans talk likes to make it seem like you never really know for sure but almost everyone knows for sure by the time they're your age whether they're male or female. If you menstruate out of your vagina you are female. If you ejaculate out of your penis you are male.

Look, being a teenager is fucking HARD. Your emotions are cranked up to 11, you have responsibility but no freedom, and you have no experience to draw on in any situation whether internal or external. It sucks. Anyone who tells you it's the best time of your life is full of shit. But it WILL end. You just have to hang in there. I experienced a major shift in my thinking and emotions when i was 19, without doing anything at all. It's just maturing.

Don't obsess about something that's distressing you as the idea of transgender clearly is. Distract yourself, challenge the negative thoughts, or just wait them out.

I think if you work on accepting who you really are - a perfectly normal 16 year old girl with plenty to offer the world - you will be much happier than obsessing over an idea you can never achieve. I suggest reading about awesome women from history who broke out of social restrictions to do exactly what they wanted, because being uncomfortable with being or looking female comes mostly from the expectations that are associated with that. From listening to de-transers, 'social transitioning' just makes the feeling of being out of place so much worse, so my gentle advice would be to just drop it altogether, give it a few months, and see how you feel.