Who do I speak to about my Landlord not lowering my rent but she lowered my roomates rent?

It's not discrimination if your landlord has a valid reason to refuse your request, a valid reason would be that you have been late with your rent in the past, making you an unreliable tenant. In all fairness she doesn't have to lower anybody's rent at all, the lease you signed states the amount of rent you have to pay and is legally binding. Rent very rarely goes down, it either stays the same or increases so your roommate was very lucky! I can only assume that he is a good tenant who always pays his rent/bills on time and that you unfortunately don't have such a good tenancy record. You could try asking her if it's possible to change the date you pay your rent if that would make it easier for you to pay on time, otherwise maybe you could save the $25 somewhere else in your budget.