The first TSA officer you will meet is the TDC, or Travel Document Checker. Your photo ID, usually a driver's license or a passport, should resemble you and your name and other info should match your boarding pass. You must be who you say you are, or you won't get much farther.
If your name is Ralph Smith and boarding pass and ID agree, it won't matter whether you are dressed as a man or a woman. The TSA officer's don't care about your clothing.
If you, Ralph Smith, are presenting as a female, you will be treated as such. If the millimeter wave scanner detects an anomaly, the general location will be flagged by a yellow patch over the iconic figure on the display. If a patdown is required it will be by a TSO of the same gender as you present. It is the scanner that determines whether additional screening will be required. After you step through the scanner look at the display. If yellow patches are on the display that is an anomaly that has to be resolved.
The TSO will tell you exactly what she is going to do before the patdown begins. You have the right to have the patdown in a private setting and to bring a friend along to witness the procedure.
The TSO's have seen about everything you could imagine, and they are not worried about anything other than whether you have dangerous contraband on your person. You will not be the first transsexual they have seen.