Using WhatsApp is a good start. You can always assume you will be tracked, but are they? Good question, it all depends on how focused the NSA is in targeting you. I've heard stories where innocent people would get mailed a terrorist recruiting site, and its on the NSA target list. So, a 2nd level of intercept might dig up something you said 2 years ago in an innocent context, but 2 years later, could be interpreted as something else, so this innocent person could wind up in the no fly list. But, if that person has been using 'Signal', their conversation would be out of reach of the NSA. Sure, they can track you, even using a dumb phone with no GPS, but they don't know what you're saying, or who you're talking about, if you use Signal. So all of this is a moot point, but when you start using encryption, use it ALL the time.
RE: Switching System 7 (SS7) Security flaws