I was told to eat foods that are higher in calories, no low fat foods at all.  I had to eat every 2-3 hours and the foods had to be really filling.  I ended up going through a whole loaf of bread everyday by myself.

With any weight issue, you have to take into account your height.  For me, my ideal weight is 55-60kgs, and even after having just had a baby, I'm probably a little on the lighter side of things and need to start eating more again.

Your body mass index is important to know.  That is your height, weight, fat/muscle ratios.  To get these, you should see your doctor and ask for help from them.  I feel that you are way to light for your height, even though you haven't given it, as by your age, you should be more than that.  You currently weigh as much as I did when I was about 13.

I have to wonder if you don't have an eating disorder though, whether by choice or by what I had, which was a lack of interest in food due to trying to keep my life together.  There are many forms of eating disorders that are recognised now, and mine was (and still is) a stress reliever type.  That is where someone ends up stressed out to the point they skip meals in order to keep going with their daily routine.  This can be very dangerous, and is the hardest eating disorder to diagnose.

Obviously, I was still told to eat healthier foods as no one recommends a diet of just cake and junk food, but I was encouraged to increase the amount of less healthy foods as well, as long as I kept a balance.