If you’re eating as cleanly as you say, the weight should be falling off of you already. If it’s not, the most likely explanation is that you’re eating vastly more junk calories than you think.
At 6’1" and 260#, unless you are strong as a bull (I’m talking 400/500/600 strong), you are likely carrying 80-100# of fat. (That doesn’t mean you have lose 80-100# to lose.) Assuming you are endocrinologically normal, as an 18 y.o. your metabolism is such that it takes a lot of calories to maintain that weight. It would be a major challenge to eat enough clean food to maintain 260#, and to do so in 3 meals would be nigh well impossible. Thus, your food choices and frequent ‘snacks’ must be much more calorically dense than you’re letting on (read: You’re eating a lot more crap than you’re admitting). No endocrinologically intact 18 y.o. gets/stays 260# eating three healthy meals a day and eating apples for their between-meal snacks.
At this point, you don’t need to count calories; you just need to cut the crap from your diet. Eat as much clean food–lean protein (egg whites, chicken breasts, 96/4 ground beef, non-oily fish), vegetables, and beans–as you want. Snack on fruit; again, eat as much as you want (except bananas–those need to be limited to a couple per day). Limit your junk food to one meal per week. If you do this, I guarantee the weight will fall off of you.
Now, eventually, your weight loss on such a program will plateau, and you will have a decision to make: If you’re happy with your body composition, you can just keep eating that way; if you want to lean out further, you’ll have to start counting calories. But that decision is several months away, and you need not worry about it right now.