I do the same thing, really. Similar background... My father's family is military, my mother's is high science, certain things are simply expected. They are good, very very good people. Very tight knit loving huge extended family. None of them know I have PTSD, although they've all seen some of the effects over the years.
I do best to avoid them when I'm not doing well.
It's been a hard realization. The first time I was doing badly I was thousands of miles away. I was simply not under their microscope. A lot less stress. This time I've been under their noses for 3 years.
I've been trying to move away from my family for the past 9mo. Just far enough to be inconvenient, about an hour or two by train. They're not the primary reason I need to move, but a bonus, I simply cannot breathe well around them, as much as they care. I have to stay close to be near my son, or I'd be in the EU (I had Italian citizenship until last year), or New Zealand, or pick halfway around the globe jus about anywhere as of 3 years ago. For a lot of reasons, no small part, being distance from my family. So that they're happy for me, instead of distressed & pissed off at me.
Their need for everything to be normal, alright, fantastiche, laudable, accomplished & achieving, etc.? Is just a helluva lot of added stress. Everything is not. It is outside of their concept of the world for that to be the case.