Google's link: operator only shows the number of high quality links that point to the URL you enter. This usually means links from pages with a PageRank score of at least 3 or 4. Note that the pages shown in the results (if any) are rarely the sources of those high quality links. They don't show the actual sources of the high quality links to prevent people from poaching good link sources. Google's been working this way for about 4 years now. If you want a more comprehensive list of the links that Google knows about, use the Links tool in the Webmaster Tools console.
It doesn't mean that you don't have back links, I used to have a site with 400.000 back links and google only showed 255
1)Actually Google does not show all back links 2) Its not updated so frequently Yes high quality back links updated soon...as its always taking time to update in google.