the difference between poco or poquito and pequeño is that poco and poquito mean a small quantity, eg a little sugar, and pequeño means a small size, eg a little glass.
poquito is sometimes used to mean very little and sometimes because people like to use the diminutive (like Scots use wee)
It is 'reirse de mi' not 'reirse de me'
me is only used for a direct object. the addition of the preposition de makes it indirect and therefore must be used with mi.
Unfortunately the rules have changed and now you can use 'solo' or 'sólo' indistinctly as motley says. I preeferred it the old way as I knew that if I could substitute solo with solamente then it had to have an accent, ie it had to be sólo.
Now you have solo meaning both alone and only.
remember that when it means alone it is an adjective and therefore has gender, solo and sola.
él está solo y ella está sola.
when it means only it is an adverb and is only solo or sólo.
as to the use of 'at me.'
it can get confusing but only because you are an English speaker and are trying to translate. There are (according to my copy of the Short Oxford) 29 different meaning/uses of at. Some of them used with verbs and some with othe parts of speech.
So the problem is which one are we using and how would we say that in Spanish.
I know that when you are learning you initially want to translate but remember that children learn a language through use not through translation.
When you ask me how to translate I need context and a full sentence. Note that translation is a difficult skill and knowing a language does not qualify you to translate. A friend of mine is a Spanish author who has had some of her books translated into English. I read one of them and if I didn't speak Spanish I would not have understood a word of what the book was about.
We have an old joke in English that is only understood by Spanish speakers. It is about this Argentine (in the original) that goes to New York and is waiting for someone to arrive. When he hears the knock on the door, he says: "Between, between no more! Drink a chair!" (we call this Spanglish)
This is translated literally from the Spanish
Entre, entre no más! Tome asiento!
There was even an journalist in Buenos Aires, Basil Thompson, that wrote a column in the Buenos Aires Herald, a British newspaper, where he poked fun at people that translated literally using phrases like "There armed itself a scandal of the great seven!"
'Se armó un escándalo de la gran siete.' is Spanish slang for there was a very big scandal or ruckus. (see escándalo can be literally a scandal but it can also be a conmotion, a ruckus. THe context will tell you.)
So the problem is to learn how to use Spanish words not how to translate English words to Spanish words.
The question should always be how do you say this in this setup not how you translate.
Well, I have spoken too long and I know it is not easy to start to think in a foreign language but you have to try or you will always speak Spanglish.