I have a website that is an Internet forum. This forum has many categories, and a single category page that contains a lot of subpages with listed threads.

This Internet forum is brand new, and about a week ago I filled it with a few hundred thousand threads. I then looked at my Google Webmasters Tools page to see any changes in indexing, but the index went up from 300 to about 1200, so that means it did not index my added threads (although it added something).

The following is what my sitemap.xml contains, which I uploaded to their website. Of course there is a lot more code, this is just a snippet for a single category. In my real sitemap file I have all the categories listed as below:

<url>
  <loc>http://mysite.com/Forums/Physics</loc>
  <changefreq>hourly</changefreq>
</url>

Now, I would expect Googlebot to go into mysite.com/Forums/Physics, and crawl through all the subpages with thread links, and then crawl inside of each thread and index its content.

How can I achieve this? Also if this is unclear, I will add a real link to my website.