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

This internet forum is brand new, and about a week ago I filled it with few hundred thousands threads. I then looked at google webmasters 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).

This is what my sitemap.xml contains which I uploaded on their website (of course there is a lot more of the code, this is just a snipped 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 google bot to go into http://mysite.com/Forums/Physics, and move through all the subpages with thread links, and then get inside of each thread and index it's content. How can I do this? Also if this will be unclear, I will add a real link to my website.