I sometimes want to be a girl strictly due to the clothes.
What about being a girl do you like?
I only wear the clothes. I have a girlfriend that supports me
It's okay to wear clothes from a different gender. You should continue to experiment if you want. If not, you might feel bad about not acknowledging your needs.
It's fine, I wear girl's stuff to show my girlfriend I love her and to please her.
If both of you are consenting, then there is no problem with it. You are harming no one with your actions at all.