I hate to be doom and gloom, BUT... i'd talk to her about making the security deposit cover last month's rent.
I'd hum and haw about having cashflow issues with moving, and she can take a look at how well you've maintained the inside in order for her to make that decision.
Right there, that's when you'll know who you are dealing with. ..
You want to bring up this topic even if just to see how she handles the discussion. That can tell you a lot about their intentions.
You should get proactive NOW.. you have nothing to lose but your own money.
I'll tell you right now, there's a very good chance that if she can find a way to keep your money, she will.
In my 'rental' experiences.... sticklers have charged me $80 to replace the drip pans for all four burners on the stove... even though I cleaned them when I left and they were not new when I moved in...(ridiculous, isn't it?)
Also, even tiny stains on the carpet could justify carpet cleaning expenses....
She could easily flat out charge you for a cleaning service to come in after you leave. (nice landlords put that up front in the contract language)
Pictures do help if you were going to court. or they may have some leverage when you fight with her about the 'bill' that she drafts up to charge against your deposit.
I've only had one nice landlord offer to use my security as last month's rent.