My first suggestion is that you separate your dialogue into paragraphs. It's a basic tenet of English prose: a new speaker means a new paragraph for the purposes of formatting. This helps the reader to separate who is speaking. It will also help you to notice when you have left out the end double-quotation ("), such as:
"Well...in that case maybe...he stammered.
The lack of the end quotation here, since you have another character speaking immediately afterwards in the same paragraph, is confusing. As a result, I found this to be a very difficult read.
Capitalization is also something you should take into consideration. As Sally is the name of your self-insertion character, her name should be capitalized. You should also look into punctuation. A question should end only with a question mark (?), not both a question mark and a period as you have them (?.).
I could not finish reading the story for the basic errors in English. I would recommend going back over this in a program that has spell-check first. You can download OpenOffice for free here: http://www.openoffice.org/. There is an extension available called After the Deadline here: http://www.afterthedeadline.com/download.slp?platform=OpenOffice. This will help catch your grammar issues, though it will not catch the issue you have with punctuation. This could be because you have also inserted a space between the end of your question and the punctuation for it.
If you wish to improve your writing, this is where I would begin. Familiarizing yourself with the rules of the language in which you choose to write is necessary to be a successful writer in that language.