Is this normal?

So I am really skinny, like really skinny. I think I weigh around 50kg (it fluctuates by a couple hundred grams each day) and I'm 5 foot 11, also I'm a guy and I just turned 16. To give you some context...
I eat a lot. On a regular day, I would eat a bowl of cereal and toast with PB and some tea, then for lunch a smallish pizza topped with cheese and salami and tomato, I would drink one of those ready made coffee cappuccino drinks from the supermarket. Then in the afternoon, I graze, normally have a slice of cake, a danish, a chocolate wafer bar thing, fruit. Then for dinner it varies, usually chicken or fish though. I rarely eat beef/lamb/pork.
I feel I should be putting on weight but I am so skinny. Why? Is it just a quick metabolism? Also I did see a doctor, I did a blood test and all they found was I was slightly anemic so I take an iron supplement pill thing everyday. Could this be caused by my very minor anemia?

I doubt its anaemia but its probably your metabolism or a genetic factor. I have a friend who's exactly like you've described and he eats everything he sees and he's basically a skeleton.

Yeah actually my dad is similar to me, and my mother as well.
The thing is I don't like being a skinny little guy...I would prefer to have a little meat on my bones...

So I am really skinny, like really skinny. I think I weigh around 50kg (it fluctuates by a couple hundred grams each day) and I'm 5 foot 11, also I'm a guy and I just turned 16. To give you some context...
I eat a lot. On a regular day, I would eat a bowl of cereal and toast with PB and some tea, then for lunch a smallish pizza topped with cheese and salami and tomato, I would drink one of those ready made coffee cappuccino drinks from the supermarket. Then in the afternoon, I graze, normally have a slice of cake, a danish, a chocolate wafer bar thing, fruit. Then for dinner it varies, usually chicken or fish though. I rarely eat beef/lamb/pork.
I feel I should be putting on weight but I am so skinny. Why? Is it just a quick metabolism? Also I did see a doctor, I did a blood test and all they found was I was slightly anemic so I take an iron supplement pill thing everyday. Could this be caused by my very minor anemia?

I'm the same, but a girl. :/

I move a lot, so I presume my weight stays the same due to this.
It could be fast metabolism, it could be wooooorms (gross, I know), but that sometimes can cause people to not gain weight although they eat like crazy.
The real thing to think about is whether you feel okay the way you are at the moment - dizzy, tired etc? Remember that you are just 16. You grow like hell and your body needs to get used to it. This also takes energy etc.

I get dizzy, when I get up suddenly but I think that is just to do with the anemia...

That's not very much food, tbh.