That's pretty epic, but u cld turn it back 2 win.

I never separate color and white

Epic fail one, check.

Second mistake was my remark to A.: "well, you don't really need a bra yet, it's not a real problem i think".

Epic fails 2 through five. It's only one incident, but it takes up a lot of space. It's just that big.

This time not just a mistake, more like an epic fail.
"OK, CALM DOWN I WILL BUY YOU A NEW ONE!" i told her.

Now I'm in deep shit, i will have to go to the lingerie store and buy another one.

Psh. That's not even a minor fail. In fact, it might start to make up for 1-5. Not that it would unfail it, just that it would be the honorable thing to do to adress the circumstances.

However...

In my mind i see myself standing there: "can i help you sir, do you need anything special?" , "nothing special ma'am, just a training bra for a 10yo girl".
Two eyes will be looking at me, telling me "this is the worst pervert ever to enter my shop".

...you could turn this into total win.

If you were to walk in, and say "I'm looking to buy some lingerie for my girlfriend. Do you have a bra suitable for a ten year old girl who's still fairly flat? Preferably with lace. I like lace..."

...you will have created epic win. Remember, when the v&/mall security/whatever arrives, to shout "I did it for the lulz!!" as you're being dragged off. It's important to get the message out.

Serious. Fucking. Epic. Win.

Of course, since you're afraid to actually provide clothes for your daughter, I doubt you have the courage and fortitude to actually walk the path of win. That's okay. It's not for everyone, brother, and only a select few are eliete enough to do what it takes to bring win into the world for great justice. Nonetheless... you should, like, totally do this; it would be win.

You are presented with a great opportunity. Use it wisely. 'n while your daughter would almost certainly want to curl up and die at the time were she with you, she'll worship you when she grows up enough to discover the dark heart of the internets.

Do it for justice. Do it for win. But most of all... do it for lulz.