Wet venting of added bathroom sketch -question is this layout OK?
Found this at https://inspectapedia.com/  Which references Maryland plumbing codes.  You should check your local code for what's appropriate in your situation.

The second table, which shows trap-vent distances says that for a 2" trap (shower) the maximum distance to the vent is 5 feet.  You're way over.  It also specifies a minimum vent size of 3"