to be sure to use the right httpd.conf you should use the following cmd:
/PATH TO APACHE/bin/httpd -f /PATH TO THE NEEDED CONF FILE/httpd.conf
The argument -f is used to specify a particular instance of the conf file.
But, the problem is probably that your apache is installed as static, so you need to recompile it after compiled and installed php.
If you do not want to recompile Apache each time you add a new module, you should install it in DSO mode (Dynamic Shared Object). In this mode you'll have just to restart your httpd after each module addition and httpd.conf modifications.
bye
oli ava