Combide My wordpress buddypress community to a newly remodeled community with no data loss (NOT A SIMPLE EXPORT or TRANSFER)

I have a WordPress site that has a buddy press community on it with forum, blogs, media, profiles, and data. This community is live and I cannot work on it while it's live so I made a [login to view URL] site where I created a complete theme with full customization's, seo, plugins, ect. Now I have the new site built with a new theme and a whole new layout and plugin options, but I need that applied to the site with all of the content, users, media, photos, community and blogs. I need the Live WordPress site content (only blogs, media, photos, forums, users, users profiles, polls, ads, activity, posts, events, friends requests, user groups) to be transferred to the new wordpress site while maintaining the new sites plugins, settings, seo, all theme design, with the current images. I don't need anything built or designed, I just need a proper export of all the content listed above without it breaking my site or erasing and overriding any content and data. I also want you to look at the server and files and make sure it's running smoothly before I launch the new site. I want to emphasize that there can't be any data loss or the new website theme changing when the data is transferred. I would do this myself but every time I transfer data it doesn't apply right and breaks the theme so I need to hire a professional. I just want to confirm this is NOT A SIMPLE EXPORT or TRANSFER. The data doesn't transfer with a simple plugin, I've had a programmer already try this and fail because it didn't match up to the users profiles when transferred and exported. This is for someone experienced.