I agree with Emmaki; you need to read up on theoretical sampling. Also each coding stage segues into the next and also happens concurrently. Therefore while 7 interviews doesn't sound too much, were they in-depth interviews? If they were only 10 minutes then it is unlikely you will get much out of them, but if, and they probably were, much longer than of course you can start to extract themes etc.
Chapter III, page 45 o.w of The Discovery of Grounded Theory (1967) is the chapter that deals with theoretical sampling. It is also covered in every other GT book.