Q: Since my iPhoto updated to Photos I cannot find my Photos which were in iPhoto before.. How can I have the same sorted system as before?

How did you move your photos to the Photos.app? Did you open your iPhoto Library in Photos?  This should have preserved all your albums. and created an album for each event.

Are really all albums missing?  Were your albums regular albums or smart albums? Not all smart albums can be migrated to Photos. It will depend on the smart rules, if they can be recreated in Photos.

See:  How Photos handles content and metadata from iPhoto and Aperture - Apple Support

I'm lost - how do I get home?

Obviously unless you give us some details it is not possible to answer your question

Basically the first time you launch Photos it migrates your iphoto library and keeps everything possible (some smart albums can not be migrated)

see How Photos handles content and metadata from iPhoto and Aperture - Apple Support

LN

Of course until you migrate your library you do not have access to it or any of its content - Either drag the iPhoto library to the Photos icon in the Dock to migrate it or hold down the option key while launching Photos and select your iphoto library to migrate and open

and the migration will follow the rules in this link from before - How Photos handles content and metadata from iPhoto and Aperture - Apple Support

LN