Does it matter what the source of calories is to fatten up ? I've had my 3% bodyfat practically my whole life (expect when I was a baby problably). I've been desperately trying to gain some fat the past month, but got no results. This is what I took in today:

>Breakfast : Half litre chocolate milk (340 kcal), Half litre whole milk (325 kcal), chocolate bun(200 kcal)
>Brunch : Big tuna salad sandwhich at school, I estimate it to be around 400 kcal
>Lunch : 5xCheeseburger at McDonalds + coke (1700 kcal )
>Afternoon : Half litre whole milk (325 kcal) + waffle (180 kcal )
>Dinner : Has yet to come.

I'm almost at 3500 kcal without dinner, I'm 5'7 and weigh 108 lbs. For over a month, I've been pushing myself to go over 3000 kcal everyday, yet I'm stuck at 3% bf. This shit can't be normal. Is my liver messed up that it can't produce fat or something like that ? Should I go see a doctor about this problem ? I don't do cardio & only started a small amount of strength training recently.