Doing six meals a day using whole foods is a bit of a chore, so don't worry about it. You can use meal replacement shakes and protein bars to fill the gaps between your whole food meals if you're into them. And since their nutritional value is printed on the box, there's no guesswork about that. For a thin person like you, adding calories in six smaller meals makes more sense than doing it in three larger ones. Also, eating some protein and carbs after a workout - preferably whey protein and high glycemic index carbs - is important.
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Chicken and ground beef are OK, as long as the chicken isn't fried and the ground beef isn't a Thickburger