We almost always get more requests for books than we have copies to send - so if you did not receive a confirmation email a recent book then, sadly, this time around, we weren't able to send you one.
We have considered sending a message to everyone who requests a book each month and does not get one but concluded that it would be more likely to confuse than clarify because many members request multiple titles each month so would get hit by a flood of emails, in amongst which, the all important one telling them they are being sent a particular book might get lost. Anyhow, looks like you haven't done too badly with regard to books recently - I count 7 books received through First Impressions in the past 2 years :)
For anyone reading this who is new to BookBrowse. First Impressions is our early review program: http://www.bookbrowse.com/arc for members. The recently launched Book Club http://www.bookbrowse.com/onlinebookclub works on a similar premise, except that instead of sending soon to be published books for review, we match members with free copies of books to discuss in the book club. While only a limited number of members can receive a copy of a book but all are welcome to join in the discussion.