The lease is the contract between the landlord and the three of you. It doesn't govern the relationship among you.
I assume that before you moved in, you discussed terms with the other girls. Things like which bedroom would be yours, what your bathroom, laundry and kitchen rights would be, how much rent you'd be paying, and what chores you'd be expected to do.
I'm guessing you didn't create a written agreement, but all that means is you have a verbal contract instead.
If you discussed parking at that time, then you need to honor what you agreed on then. You can try to renegotiate, but it's up to them whether they're willing to change your deal.
If you did not ask for parking privileges before you moved in, then even though no words were spoken about it, you agreed to live there without a parking space.
It's true that if all three of you are paying the same share of the rent and getting the same value (no bedroom is bigger than the others or has a better view, you all have equal bathroom facilities, etc.) other than the parking amenity, then for one of you to lose out on that is unfair. But your verbal contract does not have to be fair. The first ones in a shared rental can offer a "take it or leave it" deal to a prospective new roommate, and the new one has to choose the unfair deal or look elsewhere for a place to live.