I place my CF card and open LR. A different catalog opens every time??
I now have multiple catalogs and do not know where are my pictures???
I suggest to merge all catalog into one catalog. Read the tutorials for merging here: https://www.lightroomqueen.com/lightroom/catalogs/merging/
You may also want check the following setting in LR: Open the Preferences and make sure Default Catalog is set to Load most recent catalog.
Search on .lrcat and upload a screen shot of the results. What has changed in your workflow?