Messed up gallery

Hello!

I am trying to make galleries look normal but, if there’s more than a few elements, it becomes ugly, like this:

https://i44.tinypic.com/ea3zmb.png

If I add the ligthbox gallery plugin, things become even worse:

https://i44.tinypic.com/2vljfbb.png

It deforms the images.

I have tried this on the twenty twelve theme and it works perfectly. Gallery thumbs are perfect, the distance between them too, and lightbox plugin works. But damn, I prefer some options of the twenty eleven! Is there a way to fix this? I’m working with a child theme and all that stuff.

Thanks a lot!