Is this a good or a bad thing to eat for my age?

I am 17 years old I weight 147 pounds and I am 6'1" my doctor says I am a healthy weight. I use to weigh 201 pounds and got sick of being chunky and having man so I went on a diet consisting of drinking only water (I use to drink a lot of pop) and I ate a granola bar for breakfast and for lunch something healthy with some carbs for energy and for dinner I ate whatever I wanted in small portions and worked out afterwords. Well anyway I had to explain all of that before I could ask is it healthy now since I am normal now that I have a bad sweet tooth and crave sweets and eat them? I mean this is what I ate today I fruit grain bar for breakfast then for lunch I went to Mcdonald's and had a big mac a medium fry and a mocha frappe and for dinner I had Taco Bell which I ate a beefy 5 layer burrito and a soft taco supreme, then afterwards I had a sweet tooth and stopped off and ate a doughnut. I still drink only water and the reason I ate ate two fast food places today was because I went to a funeral, I usually eat home cooked meals 3-4 times out of the week. So is it healthy that I eat like this and don't gain weight, I am afraid that one day I will start gaining weight again and become fat again! I gained 7 pounds because I have been drinking protein shakes on the days I work out so that was muscle because I wanna get more muscular because I am skinny but I use to weigh 140. So please help.