Sorry to hear this is happening to you. :(
In order to be getting patted down every time, then something is causing the body scanners to trigger on that part of your body. As Azor Ahai's answer discusses, the body scanners highlight a region of your body where something was detected (or else give an ok that nothing was detected.) The agents will then pat down the area highlighted by the scanner. So, if it's consistently triggering on one part of your body, then there's something there that's triggering the scanners. Unlike metal detectors, due to the way these scanners work, this would generally have to be something on the outside of your body, such as your clothes or if you had some kind of prosthetic. Things like internal plates or rods, pacemakers, etc. should not trigger the body scanners.
So, if there's something on your shirt, bra, etc. that is especially dense and/or layered, this could be triggering the scanners. Trying different clothing options with fewer and/or less dense layers might solve the problem.
Another way to avoid this almost entirely is to get TSA PreCheck, as mentioned in the comments. As someone who travels somewhat frequently, PreCheck is great (compared to standard screening, at least.) No need to take off your shoes or light jacket. No need to take out your laptop and liquids bag. And, most relevant here, usually no body scanners (unless maybe you're at a rather small airport where they don't have a separate screening line.) PreCheck lines typically use only a metal detector for the vast majority of passengers, though they may still randomly send you through a scanner from time to time or if something triggers the metal detector.
As an additional bonus, the PreCheck lines are also usually much faster than the regular screening lanes. Even if the line itself is as long (which it usually isn't,) the line moves faster due to people not having to take off their shoes and walking through the metal detector being substantially faster than using the scanners.
Getting PreCheck by itself is $85 for 5 years, though many travel-focused credit cards include a credit that will reimburse this fee. If you travel internationally, then you might want to consider Global Entry instead, which includes PreCheck as well as providing expedited immigration control when entering the U.S. It is $100 for 5 years, though applying takes longer and is somewhat more of a hassle.
I would agree with some of the comments, though, that you may still want to complain to TSA. They are supposed to tell you what they are going to do prior to touching you if they need to conduct a pat-down for some reason.