How do I enter my room rental? The form doesn’t ask for square footage. Now it is deducting 100% of all my expenses.

Great catch, let's get you prorating. 

First, in the general property information, check that you marked "I rent out part of my home".

Second, select a method, enter percentages and numbers.  There are two options, either way you must know the percentage for the rented portion.  For my example, I will use 25% rental.

• You do the math:  Enter your %, example 75% of the mortgage interest and property taxes under deductions and credits. Enter the other 25% on sch E for the rental.
• Let the program do the math: Delete all numbers from deductions and credits. Return to Sch E to the property profile. Select that you rent part of your home, enter the percentage and select for the program to do the math. The program will put the correct 25% amounts on Sch E and pull the rest to Sch A.