Will starting a new game fix the no trans option
You don't have to start over from the beginning, unless you
want to play a completely different path (trans or non-trans).
Downloading the 12.1 update that's now linked in the OP (or applying the
bugfix update from the previous page) should be enough.
After updating, just load a save from either before the rich women's party or early on in the party. Just make sure you use a save that's from before Ryann takes her pants off and turns around to show you (with the bugfixed update, this is where the variable will be set for Ryann's gender;
if Shauna is cis female, then Ryann will also be cis female, and if Shauna is trans, you'll actually be asked if you want Ryann to trans female or cis female, i.e. penis or vagina).