I'm going to try to make my girlfriend shower when she doesn't want to
Why would you force her to shower?
I just want to make sure she's clean.
It is wrong to force people to do things they don't want to do. If she has a hygiene problem you should speak with her about it.
She should feel bad if she's dirty though.
But it sounds like you're forcing her to shower no matter what. You should just let her clean herself on her own time.