BuddyPress.org

=== I am using Platform 1.1.3 by PageLines ===

You will need to install the BP Template Pack plugin to make your WP theme compatible with BuddyPress.
https://wordpress.org/extend/plugins/bp-template-pack/
https://codex.buddypress.org/theme-development/wordpress-to-buddypress-theme/
https://codex.buddypress.org/theme-development/bp-template-pack-walkthrough-level-easy-2/

Other than that, you could create a bp-default child theme and tweak it to look like Platform theme.
https://codex.buddypress.org/theme-development/building-a-buddypress-child-theme/