Every girl is different.
You're only 13, I'm sure it will be.
Mother nature is responsible for this.

It’s totally normal for this to happen don’t worry about it if it’s no noticeable they will eventually even out

I see (I really see) that people are not symmetrical, but that way you get more in a person.

Hey lovely!

Firstly nothing to be embarrassed about at all. It’s totally normal to happen and I have the same, my left is quite noticeably smaller than my right boob. I guess it’s just one of those things.

you’re in no way a freak…don’t say that ❤️

its just something that can happen, puberty is like that . Hopefully soon your other breast will start to grow and they'll soon be even in size.

There's going to be alot of growth and changes that will make you feel embarrassed. But remember every one experiences them, and gets that feeling about something on their body. And in a few years time puberty will be over and you'll be the amazing young woman you're growing into

People are not completely symmetrical even when fully developed. People often have one foot slightly bigger than the other which comes up when fitting for shoes. I have also seen pictures where one half of someone's face has been duplicated and flipped left-right to create a fully symmetrical face and the result looks odd.

Then there can be some further asymmetry during development. For example, do you remember back to getting adult teeth in place of baby teeth? I know, for me, there was a slight delay between one side and the other. I don't remember which was first but I do remember that they weren't quite together but once the adult teeth were fully grown they were much closer to symmetrical.

So it seems to me that breasts are just similar to other things in this respect.

My left is just a tad bigger than the right. but really no one notices but me. It's probably way more common than you think.

Don’t worry about it, it totally normal to have one bigger than the other and its usually not even noticeable

Yeah, it's a common thing (from others I've talked to). My left was slightly bigger for awhile, but I really can't tell the difference a few years later

I dealt with the same thing. It's a pretty common thing

Same here.

It's more noticeable during certain times of my cycle for me.

the same